STANFORD LINEAR ACCELERATOR CENTER
Winter 1997, Vol. 27, No.4
WINTER 1997
Fermilab Visual Media Services
A PERIODICAL OF PARTICLE PHYSICS
VOL. 27, NUMBER 4
FOREWORD
2
Burton Richter
Editors
RENE DONALDSON, BILL KIRK
Contributing Editors
MICHAEL RIORDAN, GORDON FRASER
JUDY JACKSON, PEDRO WALOSCHEK
FEATURES
4
THE SINE QUA NON FOR THE FUTURE
Editorial Advisory Board
OF HIGH ENERGY PHYSICS
GEORGE BROWN, LANCE DIXON
JOEL PRIMACK, NATALIE ROE
ROBERT SIEMANN, GEORGE TRILLING
KARL VAN BIBBER
The DOE’s new Associate Director of High
Energy and Nuclear Physics discusses the
promise and problems of international
scientific collaboration.
S. Peter Rosen
Illustrations
TERRY ANDERSON
Distribution
12
RETROSPECTIVES ON INTERNATIONAL
COLLABORATION
Four different perspectives on international
collaboration in high energy physics are
presented.
Gordon Fraser
Hirotaka Sugawara
Alexander N. Skrinsky
Zhou Guang-Zhao
20
U.S. COLLABORATION
ON THE LHC PROJECT
A member of the U.S. collaboration, who has
been involved since its beginnings, discusses
the history of the Large Hadron Collider
and its importance to U.S. particle physics.
George Trilling
27
THE ATLAS INNER DETECTOR
The U.S. leader of one of the major systems
describes what it is like working on the inner
tracking detector for the ATLAS project
at the Large Hadron Collider.
M. G. D. Gilchriese
CRYSTAL TILGHMAN
The Beam Line is published quarterly by
the Stanford Linear Accelerator Center,
PO Box 4349, Stanford, CA 94309.
Telephone: (650) 926-2585
INTERNET: beamline@slac.stanford.edu
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Issues of the Beam Line are accessible electronically on
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pubs/beamline. SLAC is operated by Stanford University
under contract with the U.S. Department of Energy. The
opinions of the authors do not necessarily reflect the
policy of the Stanford Linear Accelerator Center.
Printed on recycled paper
INTERNATIONAL COOPERATION:
31
THE CMS HADRON CALORIMETER
The CMS experiment will use a large general
purpose detector to study proton-proton
interactions at CERN’s Large Hadron Collider.
A major subsystem, the hadron calorimeter,
will measure the energy flow in these
interactions.
Dan Green
35
INTERNATIONAL COLLABORATION
ON LINEAR COLLIDER RESEARCH
AND DEVELOPMENT
Physicists around the globe are cooperating
on designs for a trillion-volt linear collider.
Gregory Loew and Michael Riordan
53
DATABASES AND INTERNATIONAL
COLLABORATION
Pat Kreitz and Michael Barnett
Reidar Hahn, Fermilab Visual Media Services
CONTENTS
43
THE UNIVERSE AT LARGE
What, and Why, Is the International
Astronomical Union?
Virginia Trimble
55
FROM THE EDITORS’ DESK
56
CONTRIBUTORS
60
DATES TO REMEMBER
Lawrence Berkeley National Laboratory
DEPARTMENTS
FOREWORD
I
N MANY DIFFERENT FIELDS , ranging from astro-
physics to molecular biology, scientists have pushed back the
frontiers of their research so far that important advances can
now occur only by making huge investments in new equipment. This
is certainly true of high energy physics. Having answered the “easy”
questions, we now face the really tough ones—such as why quarks
and leptons appear in three distinct families and sport the peculiar
masses they bear. These are the kinds of issues that the abortive
Superconducting Super Collider was designed to address and that
CERN’s Large Hadron Collider will take up early in the next century.
If we can learn one thing from the cancellation of the SSC, it should be
that—given all the competing interests and demands on the public treasury
that governments around the world must satisfy—it is unlikely that any
single country will come up with the many billions of dollars, deutschmarks,
or yen needed for the most advanced scientific projects, unless there are immediate economic benefits. The rewards of basic research, both the knowledge gained about Nature and its impacts upon future societies and
economies, are available to all. Individual governments are still quite interested in supporting scientific research, but they are reluctant to foot a
majority of the bill on their own when many others will benefit. Thus
scientists have to find effective ways to share their major costs across national boundaries.
Scientific megaprojects that must be located within a single country,
such as fusion reactors or particle accelerators, present a particularly thorny
problem. As we learned from the SSC episode, support was widespread
until a specific site was chosen in one particular state. How much more difficult must it be for governments to dip into their coffers to fund large
facilities located in other countries? So far we have dealt with this problem
in the high energy physics community mainly by sharing the detector costs
while letting the host country or region pay for the accelerator or collider.
But to build the multibillion-dollar colliders needed in the future, we must
follow the lead of our European colleagues and learn how to share these
costs, too.
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WINTER 1997
The author and Hirotaka Sugawara,
Director General of the Japanese
High Energy Accelerator Research
Organization (KEK), at the Next
Linear Collider Test Accelerator
being built cooperatively by the
United States and Japan.
There is another problem to be
faced as well—the global distribution of the biggest scientific
projects. If it is unreasonable to
expect any single country or region to support such a megaproject on its own, it is equally unreasonable to expect any country
or region always to pay for projects built elsewhere. This is especially a problem for high energy physics.
International funding and siting of our largest projects are more difficult
than for projects such as deep-sea drilling, Antarctic research stations,
and the Space Station, which have no specific national home. We have to
look across all scientific fields—including, for example, fusion and nuclear
physics—when considering the geographical distribution of gigantic facilities. Only in this way will there be enough megaprojects to achieve a global balance. Physicists don’t like this “basket” approach, but politicians will
find it more acceptable.
This special issue of the Beam Line is devoted to the question of international collaboration in high energy physics. It offers perspectives and
insights on the programs in Europe, North America, and Asia. And it chronicles some of the international efforts currently under way to design and
build the next generation of particle colliders and detectors needed to study
physics at the trillion-volt energy scale. I recommend it to all people
interested in the future of high energy physics.
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3
The Department of
B
Energy’s new Associate
Director of High Energy
and Nuclear Physics
discusses the promise and
problems of international
scientific collaboration.
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Y ITS VERY NATURE, physics is a science that knows no
national boundaries. Particles move according to the same laws
of motion no matter whether they be located in Alaska, Africa,
or the South Pole. Quantum mechanics is equally valid in a laboratory in China as it is in Europe. Indeed we believe that the laws of
physics, those known today and those yet to be discovered, apply
throughout the Universe and govern its destiny. Thus it is not surprising that physicists come from all corners of the globe, and that
transnational interactions and collaborations are second nature to
them.
Initially drawn together by mutual interest, these collaborations have become more and more necessary as the experimental
tools of the field have grown in size and cost. After World War II,
for example, the nations of Western Europe recognized that in
order to play a significant role in the then burgeoning field of
nuclear physics, they would have to pool their resources and work
together. In 1954, they signed the convention creating the Conseil
Européen pour la Recherche Nucléaire (CERN), which has since
become one of the great scientific laboratories of the world and a
model for peaceful international collaboration.
Individual nations in Europe did not forswear building accelerators entirely. France and the United Kingdom built proton
machines (see the essay by Gordon Fraser on page 12), and
Germany the DESY electron synchrotron, but they were of much
lower energy than the CERN proton synchrotron. The DESY
machine was the highest energy electron machine of its time, and
the laboratory has been the most successful one in Europe apart
from CERN. As is always the case, friendly competition is a spur
to excellence.
T
ODAY WE ARE EMBARKING ON A NEW ERA
of international cooperation, the next step beyond the
regional cooperation of which CERN is the prime example.
Until now, it has been the practice for regions such as Europe, or
super-large countries like the United States and Russia, to build
the machines that accelerate particles to higher and higher energies on their own, and for international collaborations to build the
detectors that are used to study the collisions of energetic particles
and analyze their interactions with all kinds of targets. At
Fermilab, for example, the Tevatron was built by the United States
government, through the agency of the Department of Energy, but
the two detectors, CDF and D0, were constructed with significant
contributions from Italy, France, Japan, Russia, and other countries. Similarly, Super Kamiokande, a 50,000-ton water detector
designed to detect neutrinos from the atmosphere and the sun, and
to search for proton decay, was built by Japan with a significant
contribution from American physicists. With the Large Hadron
Collider (LHC), however, not only the detectors but also the accelerator itself will be built at CERN by a supranational, interregional
collaboration.
In this respect the LHC will not only push the energy frontier
far beyond the energy of the Tevatron, but it will also test the ability of different regions of the world, in particular Europe, the United
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5
States, Japan, Russia, India, and other countries, to work together
in the creation of major new scientific facilities. Europe will still
play the major role, since it is providing the site, the infrastructure,
and most of the cost. Nevertheless, the United States and Japan
will be responsible for the technically challenging magnets of the
interaction region, a key element in the successful utilization of
the accelerator, and other non-members will contribute important
components in additional areas of the machine.
The driving forces behind this move to interregional cooperation are twofold. As high energy physics continues its march
towards higher and higher energies in pursuit of the fundamental
structure of matter at smaller and smaller distances, it must build
larger and larger machines at greater and greater cost over longer
and longer periods of time. Obviously cost and time are coupled;
the more adequate the money flow, the less time is needed to
complete the project. The cost has now become so large that no
single country is prepared to build a very large machine by itself
on a practical time scale. The sad history of the Superconducting
Super Collider (SSC) is sufficient to make the case regarding cost
alone. And the speeding up of the LHC completion schedule by
three years as a result of non-member contributions speaks to the
issue of time. We have reached the point where the entire international community of high energy physicists must work together to
achieve its goals on practical time scales.
By practical time scale, I mean the length of time a physicist is
prepared to invest in the building of an accelerator and the
requisite detectors in order to perform significant experiments. If
we take the typical career-span to be forty years, including six to
seven years in graduate school, and allow about ten years after the
PhD to gain tenure, then an incoming graduate student has about
sixteen years in which to establish her- or himself as a physicist of
tenurable quality. An established physicist, on the other hand, will
not be under the same time pressure, but nevertheless will want
to make as significant a contribution to the field as he or she can
within the allotted span of time. Students entering the field late in
the design and construction of the facility will obviously be in the
best position to benefit from its use. Given all of these considerations, I would suggest that we should plan to construct and
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commission new machines plus detectors within seven to ten
years—and no longer—in order to provide a real incentive to
physicists to commit themselves to these large projects.
An important issue in the interregional construction of accelerators is going to be the actual location of a major laboratory. As
long as the site remains unchosen, all contending partners have a
chance of gaining the prize. Once the choice is made, however,
does the support for the project by the losing partners begin to
soften? Even in large countries like the United States, this becomes a problem, as happened in the case of the SSC. Almost as
soon as the Texas site was chosen, political support for the project
from other contending states began to disintegrate, and this helped
to terminate the project in the end. Could the same behavior
occur on the international scene? Certainly, we hope not, and
indeed we will need to secure firm commitments ahead of time to
ensure that this problem does not arise.
Another important aspect is the nature of the site: do we build
upon existing facilities, or do we start with a new “green-field”
site? Europe has concentrated most of its resources in one site,
namely CERN, and thus has a significant infrastructure upon
which to build: the pre-accelerators and injectors, civil facilities,
and technical support which are so necessary to the successful
functioning of large projects. Clearly this saves a great deal in
terms of both cost and time; however, the CERN site is now at its
physical limit and is probably at the end of the road unless accelerator technology can be greatly improved. The SSC, on the other
hand, was to be located on a green-field site, which obviously
required the building of a total laboratory from the bottom up.
This adds to the cost of the project and also to the time for completion; but it does provide the opportunity to do everything at the
state of the art and to leave room for future extension. In other
words an existing site, while it may have the infrastrucure, might
not meet all the long-term requirements for a new project.
Besides the physical and technical aspects of a green-field site,
there are organizational, or, if you like, sociological issues. What
body will be responsible for the new laboratory, and how will individual countries relate to it? How will the laboratory be governed and managed? What scientific staff will it have, and how
BEAM LINE
7
Hirotaka Sugawara, Director
General of the Japanese High
Energy Accelerator Research
Organization (KEK), and John
O’Fallon, DOE’s Acting Associate Director of High Energy and
Nuclear Physics, shake hands
after signing the U.S./Japan
Agreement for Cooperation in
High Energy Physics in May
1996 at the 18th meeting of the
U.S./Japan Committee.
(Courtesy Brookhaven National
Laboratory)
will they relate to its user community? Under what conditions
will users work at the facility: open access based on scientific
merit as envisaged in the ICFA guidelines; or “pay to play,” which
would require a contribution towards the cost of the facility and
possibly consideration of operating costs? What status will employees of the international laboratory have in regard to the host
country? What will be the official language of the laboratory?
Obviously there are many more questions of this nature that will
have to be answered.
At this time CERN itself is one model to follow. It has certainly
worked successfully in the physics arena and has much to commend it. Nevertheless, other models should be examined, if only
because they might raise important questions that are not readily
apparent in the CERN model. Other fields of science—astronomy
and space, for example—use models in which use is allocated to
individual countries based upon their contribution to the construction of the facility; each country is then free to allocate its
allotment to individual scientists on the basis of scientific merit,
or other criteria. The Megascience Forum, an activity of OECD to
lay groundwork for large international science projects in many
fields, is presently engaged in a study of all of these issues as they
relate to international cooperation.
I
N CONTEMPLATING CONSTRUCTION PERIODS
that are long compared to the timescale of electoral politics, it
is not unreasonable to ask whether the United States government can be relied on to stay the course once the construction of
an international project has begun. One cannot, unfortunately,
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WINTER 1997
make any absolute prediction because so many factors can change
markedly over a decade: political moods shift and change, and
what may be popular today may become anathema tomorrow; the
economy may undergo significant changes for the better, or for the
worse; the social climate may bring to the fore issues of great
moment that may disrupt the smooth flow of life. Barring such
dramatic events and assuming that societal life will make a relatively smooth progression from one epoch to another, I believe
that the United States can be relied upon as a partner provided
that three basic conditions are met.
The first is that the case for building the facility, both the scientific arguments and the attendant benefits to society, must be
made honestly and clearly, without hype. We must not promise
the moon, either scientifically or in terms of spinoffs, but we can
argue for extending the envelopes of science and technology by undertaking challenges that have never been faced before. We cannot
predict the outcome, nor the benefits, but history does show that
on some time scales, which may be ten years or fifty years, there
are real gains to be made in science and in tools useful to society.
An important part of this argument, I believe, is the benefit to
other sciences: high energy physics has borrowed techniques from
other sciences, but in return, it has provided them with major new
tools. Synchrotron light sources, for example, are of ever growing
use in biology, chemistry, and materials science, and they are a
direct outgrowth of accelerator science pioneered by high energy
and nuclear physics.
I also believe that we must begin the effort to develop support
for the project at an early stage, not just within the high energy
physics community, but also within the broader community of
science and the general public. Outreach must be made to
Congressional delegations, local citizens, and industry so as to
build a consensus strong enough to withstand any vigorous challenges. The American political system works well when consensus exists for a project, but it does not automatically build
one. As Neal Lane, Director of the National Science Foundation, has pointed out, leadership from the science and engineering communities requires a much more public and civic
persona.
BEAM LINE
9
The second condition is that we must do, and be seen to be doing, a thorough job of establishing the total project cost and funding
profile. Once we have set these parameters, we must live within
them, even if it means that we must do some limited descoping in
order to do so. Time, in the form of upgrades and accelerator improvements, is our ultimate contingency, but we cannot afford to
give even the slightest hint, after the project has started that the
costs are about to escalate out of control. To do so would undermine
credibility and invite the same kind of assault that hit the SSC.
Finally, the project must be technically successful, meeting its
milestones as close to the planned schedule as possible. We all
know that in any major project there will be hitches, to greater
and lesser degrees, but as long as we are open and honest about
them, and as long as we can show that we are making serious
efforts on the appropriate scale, I do not believe that Congress will
lose faith in us. Naturally, an overall record of real progress helps
enormously in this regard. Thus, I am reasonably sure that Congress will continue to support a large international project as long
as we can be seen to be meeting the expectations that we create.
I
T IS MY PERSONAL BELIEF that international collabora-
tion in all aspects of high energy physics is the sine qua non for
future progress in the field. Because of the universality of
physics, such collaboration comes naturally to physicists themselves, but, unfortunately, it does not come so easily to the governments to whom high energy physicists must turn for the
resources they need. Governments tend naturally to think in
terms of national interest, and so it becomes necessary to convince them that thinking internationally is as much in the
interest of national scientific development as it is for trade and
for defense.
It behooves us therefore to create institutions within the international scientific community that are truly representative of that
community and will have credibility with governments. Such
institutions should have high visibility within the high energy
community and derive their authority by interacting with it
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Zhou Guangzhao, Special
Advisor, Chinese Academy of
Sciences, and the author sign
the U.S./Chinese collaboration
agreement in November 1997.
regularly on all issues of great moment. Their major roles will be
to develop a consensus for the next step in high energy physics
and can make the case effectively for new international facilities.
They can also facilitate the early international planning and joint
R&D that are keys to success.
The International Comittee for Future Accelerators and the
International Union of Pure and Applied Physics can certainly provide a basis for this activity, but they need to be significantly
enlarged and become more visible in relation to high energy
physics. The Megascience Forum is also a possible vehicle for creating and developing the needed institutions. Other avenues
should also be explored.
In conclusion, I would like to say that international cooperation
in high energy physics serves a deeper purpose of providing a
model for cooperation and reconciliation amongst nations that
have, at one time or another, been bitter enemies. This was one of
the motivations for the establishment of CERN; the laboratory was
able to build upon the natural ties among physicists, and help to
bring about reconciliation in Europe. Let us use them for a similar
purpose on a global scale.
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11
Retrospectives on Intern
I
N THE NEXT FEW PAGES we present four different
perspectives on international collaboration in high
energy physics:
• Gordon Fraser highlights the origins of panEuropean cooperation at CERN and DESY.
• Hirotaka Sugawara frankly appraises the
Japanese experience and plans for future
colliders.
• Alexander Skrinsky reviews the increasing
reliance on international exchanges in the
Russian program.
• Zhou Guangzhao explains how international collaboration has been the key to China’s
emergence as a prominent contributor to
the field.
Taken together, these articles show how international collaboration has increasingly knit the community together. It has indeed become, in Peter
Rosen’s apt phrase, “the sine qua non of high energy
physics.”
All four articles begin on these two pages, 12 and
13. Then they continue as separate columns on pairs
of facing pages through page 19 (look for the relevant
author’s picture at the top of each column).
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Gordon Fraser, Editor, CERN Courier,
Geneva, Switzerland
A
S THE ECHOES of
World War II died away,
physicists returned to
traditional research and teaching
interests. In the United States,
federal scientific research expen-
diture had increased tenfold during
the war and maintained this growth
over the next decade. In war-torn
Europe, postwar funding was less
generous, but scientists—with Niels
Bohr in Copenhagen as a father
figure—had immense prestige.
Spurred by fresh cosmic-ray discoveries and with strong political and
scientific motivation for particle
accelerators, France and the United
Kingdom pushed ahead with flagship proton machines, culminating
with the 3 GeV Saturne synchrotron
in 1958 and the 8 GeV Nimrod machine in 1963.
Postwar Europe was in transition.
The militant national pride that had
ational Collaboration
Hirotaka Sugawara, Director
General, High Energy Accelerator
Research Organization, Tsukuba,
Japan
Alexander Skrinsky, Director, The
Budker Institute of Nuclear Physics,
Novosibirsk, Russia
Zhou Guangzhao, Special Advisor,
Chinese Academy of Sciences,
Beijing, China
I
W
C
feeling confident about the future.
The cost of high energy physics is
ever increasing and the only way out
is to share it among interested countries. However, some physicists accept this idea rather reluctantly and
only when it is convenient for their
purposes. The failure of ICFA evidently demonstrates the unwillingness of physicists to clearly define
mechanisms to promote world-wide
collaboration.
High energy physics has a clearly defined set of research tasks to pursue for the next 10 to 15 years. The
most important issues in high energy
physics in the next few decades will
be to establish the Standard Model
east-west contacts between scientists began. Nuclear and elementary
particle physicists played the leading role in this process. At the time
it was hardly a trivial matter to discuss interesting and intriguing problems in fields so close to the bomb.
But many physicists on both sides of
the “Iron Curtain” understood—
perhaps better than anybody else—
that international collaboration is
vitally important both for healthy
progress in understanding Nature,
and for eliminating the historical, artificial divisions, and confrontations
among the nations of the world.
Contacts and collaboration with
foreign physicists became part of
Research in Dubna, where Chinese
physicists worked with foreign colleagues and obtained many interesting results. Beginning in the late
1970s, following the “Open Door”
policy established by Deng Xiaoping,
international cooperation in high energy physics entered a new era. In
1979 China and the United States established the PRC/U.S. Joint Committee for Cooperation on High
Energy Physics. The Chinese Academy of Sciences has since entered cooperative agreements with high energy physics laboratories all around
the world. Hundreds of Chinese
physicists, engineers, and students
have worked in these labs and
AM WORRIED. I am wor-
ried about the future of high
energy physics. I am worried
about the future of international collaboration in high energy
physics. Paradoxically, I am also
ORLD WAR II, the
Cold War, and a very
real possibility of
World War III loomed over the
intellectual climate of the mid1950 s, when the first postwar
HINA’S HIGH energy
physics was developed
with the aid of international collaboration. During the
1950s, the country was a member
of the Joint Institute for Nuclear
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13
engendered two world wars had given
way to a new humility and a desire for
international cooperation. In 1946, Churchill spoke of
a “United States of Europe.” Under the new United Nations, specialized agencies were also fostering international cooperation. Subnuclear physics, riding the crest
of a wave in the United States and with Europeans anxious to make up lost ground, was an obvious focus. At
a 1950 general meeting in Florence of UNESCO, the new
United Nations’ Educational, Scientific and Cultural
Organization, Isidor Rabi was a U.S. delegate. Recently
an instigator of the Brookhaven National Laboratory
(BNL), run by a consortium of East coast U.S. universities, he saw that it could serve as a role model for Europe.
But the idea of a European laboratory already had two
selfless champions—Pierre Auger, French scientist and
UNESCO’s Director of Exact and Natural Sciences, and
Italy’s Edoardo Amaldi, a former colleague of Enrico
Fermi. So thoroughly did they do their work that only
a few months later, an ambitious resolution for the
nascent European laboratory aimed to build an accelerator more powerful than the Cosmotron and Bevatron
then under construction. As astute diplomatic moves
made the Conseil Européen pour la Recherche
Nucléaire—CERN—a reality, European accelerator experts faced the challenge of building a world-class accelerator in Geneva. In August 1952 a small party went
to admire Brookhaven’s progress towards a successor
to the Cosmotron.
In August 1952, a visit to Brookhaven National Laboratory by a
group from an embryo CERN helped bring about the development of the strong focusing technique which revolutionized the
design and construction of synchrotrons. Left to right are
George Collins, Chairman of BNL’s Cosmotron department; Odd
Dahl, in charge of CERN’s synchrotron project; accelerator pioneer Rolf Wideröe of Brown Boveri, and Frank Goward of CERN.
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on a firm ground and then to find evidence for or against supersymmetry.
It will also be very important for non-accelerator physics
to search for a possible grand unified scale or even the
Planck scale.
We will need a linear collider to complement the LHC,
a 100 TeV scale pp collider, and perhaps a muon collider to complement the pp collider; we also need several
large scale non-accelerator devices. The problem is to allocate these facilities in a reasonable way among the
countries or the regions willing to share the cost. Due
to current economic conditions, together with technological capabilities, these countries are most likely to be
in Europe, North America, or Asia. However, there is no
agreed upon mechanism by which physicists can decide
the countries or the regions.
My worry is not just about high energy physicists’ reluctance to engage in genuine international collaboration in accelerator management, but also about the attitude of scientists outside high energy physics.
Everywhere I hear the cry of anti-big-science mobs. High
energy physicists are partly responsible; there has been
a lack of effort to communicate well with their neighboring scientists. I find in many cases well established
scientists in other fields are envious of us. I believe that
good scientists are interested not only in the success
of their own field, but also in the advancement of related
or even unrelated fields.
Another worry is about our relationship with politicians and government officials. Obviously, in democratic systems we must respect decisions made by our
elected representatives; it is also our task to work hard
to see that these decisions are made on their scientific
merits. The same applies to our interactions with officials in governmental bureaucracies. There are some international organizations that can potentially have a real
influence on science policy, such as UNESCO and OECD;
however, both have real limitations. First, the U.S. does
not belong to UNESCO. Secondly, the OECD was first created to protect the interests of postwar western European nations, so European countries are over-represented
and Asian countries are under-represented for discussing
big-science matters.
Let me turn to the linear collider issue. In 1986 the
Japanese high energy physics community decided that
it would participate in a foreign hadron collider project
daily life for Russian high energy physicists and laboratories after the 1963 International Accelerator Conference at Dubna. At this
meeting, colliding-beam activities were presented globally for the first time. And friendly collaboration began between the
Princeton/Stanford and Novosibirsk groups.
Two years later
this rivalry led
to the world’s
first experimental results from
electron-electron
colliding beams
at Stanford and
Novosibirsk, followed shortly by
the world’s first
electron-positron
experiments at
Novosibirsk.
This was the
real beginning of
Beginnings of the long-term collaboration the now-domibetween SLAC and the Institute of Nuclear nant collider era
Physics. Gersh Budker, right, and Wolfgang in particle physPanofsky at the INP in Novosibirsk, 1975.
ics. Wolfgang
(Pief) Panofsky and Gersh Budker contributed much
effort and enthusiasm to increase the scope of this cooperation. During the 1960s, however, their efforts were
not completely successful—mostly because of political reasons. But, unfortunately, even now, when almost
all external political obstacles have disintegrated, the
Novosibirsk-SLAC collaboration is far smaller in scale
than the Budker Institute of Nuclear Physics collaboration with CERN, DESY, and KEK. We could definitely
do much more together.
In 1956 the Soviet Union brought scientists together
from different socialist countries by organizing the Joint
Institute for Nuclear Research at Dubna. Around 1970,
CERN and groups from its Member States made important contributions to the Institute of High Energy Physics
at Protvino, site of the 70 GeV proton synchrotron—
at that time the biggest accelerator in the world. Since
obtained extensive experience, making important contributions to many
high energy physics projects.
Without successful cooperation with physicists and
laboratories in the United States, Europe, and Japan, the
Beijing Electron Positron Collider (BEPC) would not have
been built on schedule and within budget. And it would
have been impossible to have reached the design luminosity so soon after commissioning it. Physicists from
ten American institutions have since been working on
the Beijing Spectrometer (BES) at BEPC. This collaboration has been very successful, obtaining many impor-
Chinese physicists with U.S. collaborators working on the
Beijing spectrometer.
tant results on tau-charm physics, including a precision
measurement of the tau lepton mass and measurements
of the Ds and ψ’ mesons.
In addition, Chinese high energy physicists have
joined international collaborations on experiments all
over the world. Our physicists and engineers have made
important contributions to the L3, ALEPH, AMS, LVD,
and other experiments. They are also making major contributions to the construction of the two B factories and
other particle accelerators.
BEAM LINE
15
While preparing for their visitors,
Brookhaven physicists came up with
the idea of strong focusing, and magnanimously shared
with their European colleagues the insight that synchrotrons could be made more powerful. CERN gratefully
took the baton and ran with it. In a startling demonstration of what European collaboration could achieve,
CERN’s synchrotron began operations in November 1959,
several months before Brookhaven’s Alternating Gradient Synchrotron; directed by John Adams, the new CERN
machine delivered protons at 28 GeV, then the world’s
highest energy. It was the start of a U.S.-European tradition of close collaboration tempered by friendly rivalry.
Although the young upstart CERN won that race, exploiting the new synchrotrons was a different matter.
Within a few years, the Brookhaven AGS produced major discoveries—the muon neutrino, CP violation, the
omega minus. Watching enviously from the wings, CERN
had to wait until 1973 before its first important breakthrough, the discovery of neutral current. Meanwhile
CERN’s next big machine, the Intersecting Storage Rings
(ISR), the first proton-proton collider, cruised into action
in 1971. Although a triumph of machine building that
explored promising new horizons, the initial harvests of
physics results were again disappointing.
CERN had learned its lesson for its next project, the
proton-antiproton collider. A distinguished tradition
of machine building, consummate machine expertise
gained from the ISR, and the physics vision of Carlo Rubbia set the stage for the historic discovery of the W and
Z particles in 1983. With Simon van der Meer’s development of stochastic cooling, a key accelerator technique again crossed the Atlantic, but this time it went
from east to west.
But Europe has more than the CERN string to its bow.
In parallel with international efforts, its nations initially
continued their individual aspirations. Germany, a CERN
founder nation, had no national accelerator. To rebuild
a tradition, pioneers such as Wolfgang Paul, Wolfgang
Gentner, and Willibald Jentschke pushed for the apparently less glamorous electron synchrotron route.
In February 1964 the new Deutsches Elektronen
Synchrotron—DESY—began operations in Hamburg at
6 GeV; until the arrival of the 20 GeV Stanford linear accelerator in 1966, it provided the world’s highest energy
electrons. DESY capitalized on the trend to electron16
WINTER 1997
and it also would build a domestic linear collider. The High Energy Committee action plan, issued in 1995, states that Japan wants
to be the host country for an international linear collider
project. The Asian Committee for Future Accelerators
(ACFA) supports this action plan. There seems to be a
growing consensus among Asian countries that a linear collider project is an appropriate project for AsianPacific countries to participate in and that Japan should
take the leadership in this project.
The U.S. failed to build the SSC; a high energy physics
facility located in the U.S. is certainly needed. It is up to
the U.S. high energy physics community to decide which
project is the most suitable, given the present circumstances. If a linear collider is selected, a serious consultation between U.S. and Japan becomes necessary.
SLAC and KEK are now working together in the R&D
effort for a linear collider within the framework of worldwide collaboration. We are trying to strengthen the effort of the two laboratories by making it more formal.
This initial formal agreement will not be to make a common design, but to study together the problems of designing a linear collider, although I believe that we have
to proceed with a common design, eventually. The Japanese high energy community decided recently that it
wants to have more time to consider the issue before
it makes a final decision on whether or not to proceed
to the common design stage.
The linac for the accelerator test facility at KEK.
An international team from Japan, India, the Republic of
Korea, and Russia participate in a joint test of the prototype of
a cesium iodide electromagnetic calorimeter at the tagged
photon beam for a future KEK B factory experiment, BELLE.
This photo was taken at the Budker INP in Novosibirsk.
actively at practically all the major high energy physics
centers in the world, while foreign scientists are involved
in experiments at Novosibirsk and Protvino. And use is
made throughout the field of well-known Russian inventions and developments such as electron cooling of
proton-antiproton and heavy-ion beams, and high-
SLAC
then, Russian groups have taken an increasing role in experiments at CERN,
Fermilab, and other western laboratories. A new scale
of collaboration began on the LEP collider at CERN, where
several Russian labs and groups made major contributions to the big L3 and DELPHI detectors and played
important roles in these experiments.
After Perestroika, which brought many good and bad
things to Russian life, all
Russian science (including high energy physics)
suffers from severe economic difficulty. (See
Sergei Kapitza’s article,
“The Future of Science
in Russia,” in the
Fall/Winter 1993 issue of
the Beam Line, Vol. 23, No. 3.) International collaboration has become essential to the survival of the existing
Russian groups and for attracting bright young people to
high-energy physics. Russian physicists now collaborate
One of the most important fundamental research fields, high energy
physics is also Big Science, requiring large amounts of
manpower and resources, which makes international cooperation essential. The world community is pooling
every possible effort to overcome the budget challenges
and making great endeavors at both the high-energy frontier, with large colliders such as the LHC, and the highprecision frontier, with high-luminosity particle factories. We are confident that international cooperation
in high energy physics will be further enhanced during
the next century. The Chinese government has given
this research strong support, but as a developing country, China can allocate only limited resources to the field,
thus making international cooperation crucial. It allows
foreign physicists to do research in China, and our own
physicists to work at frontier experiments all over the
world, following the latest developments.
Chinese physicists are now discussing further development of the BEPC facilities to do high-precision
measurements in the tau-charm energy region from 3 to
5 GeV. Such a Tau Charm Factory with a luminosity
of 1033 cm−2sec−1 would allow very accurate measurements of light-hadron spectroscopy, especially searches
for glueballs and quark-gluon hybrid states, as well as
searches for CP violation in tau lepton and D meson
decays. The proposed Beijing Tau Charm Factory (BTCF)
will proceed in three steps—feasibility study, research
and development, and official construction project. So
far the Chinese government has supported a feasibility
study on the BTCF, which was reviewed by an international panel at the end of 1996. Another possibility is for
us to upgrade BEPC into BEPC II, having a luminosity
of 1032 cm−2sec−1, which would still be sufficient to do
most of the research on light-hadron spectroscopy, including the work on glueballs and quark-gluon hybrids.
We will do R&D work for both the BTCF and BEPC II, with
a final decision to be made around the year 2000. Foreign
physicists are welcome to participate in this project; their
experience and technology will prove very useful. And
foreign contributions to the accelerator and detector
would help to get the project approved by the Chinese
government.
Another fruitful international collaboration is taking
place in Yangbajing, Tibet, where a large air-shower array is being built at 4300 meters above sea level by
BEAM LINE
17
positron colliders, first with DORIS,
then with PETRA. Europe’s initial wave
of postwar machines was the culmination of national
aspirations. To coordinate these aspirations with science, the European Committee for Future Accelerators
(ECFA) was formed during Victor Weisskopf‘s mandate as
CERN Director General from 1961–1965.
For its long-term future, CERN set its sights on a large
electron-positron collider. But fertile minds had been exploring a radically different route, electron-proton collisions, to probe the structure of the proton in new depth.
Deftly orchestrated by ECFA, CERN got LEP and DESY
got HERA. In a curious twist of tradition, CERN, a proton
laboratory, had to learn how to handle electrons, while
DESY had to take protons on board. Both laboratories
took the challenges in stride, adding new depth to
Europe’s complementarity of particle beams.
CERN had demonstrated the effectiveness of formal
international collaboration, with assured funding and
guided by vision. In CERN’s parliament, or Council, representatives from Member States vote on important
issues, such as major new scientific projects, which require prior Council approval before becoming an integral part of the ongoing program. This approved program
is then the responsibility of CERN management; CERN’s
budget, itself governed by a rolling plan periodically updated by Council, finances this program. In this way, approved projects are administered according to their scientific merit and are sheltered from various political
pressures in the member States. In building HERA, DESY
had taken another approach, inviting international partners to contribute to a shopping list of equipment and resources in return for a research interest in the new facility. There was more than one way of going international.
CERN had written itself a long-lived research ticket
by building its LEP tunnel large enough to house a subsequent proton collider, the LHC. LEP is the largest electron synchrotron ever built and may hold that record forever. Crippling losses due to synchrotron radiation mean
that higher energy electron machines must be linear colliders. DESY dutifully prepared for the future, pushing
accelerator technology on several fronts. Recent achievements using superconducting radiofrequency cavities
have shown that this approach may be a prime contender
to power a large electron-positron linear collider to
complement the LHC in the next century.
18
WINTER 1997
International collaboration,
whether in accelerator R&D, particle
research, or laboratory management, is not just a matter of physics. It is a matter of language, beliefs, education, and daily life. In fact, it is a matter of an encounter
of all aspects of different cultures. In this respect I envy
California which is already very open, multi-cultural,
and multi-racial. I love that aspect of Californian style;
I want Japan to be more like that and I am glad that there
is a persistent and growing tendency in various sectors
of Japanese society to make it more open.
Damping ring in the Accelerator Test Facility at KEK.
What a physics laboratory like KEK can contribute to
this end is to build a project like a linear collider with
genuinely international management and research
programs, inviting people from California and the rest
of the U.S., from Asia, from Europe, and from all the rest
of the world to participate in the project. This has to
be done in such a way that our colleagues at SLAC will
feel happy about it. Things also should proceed gracefully. I am confident that it can be done. But I am worried. I am very confident, but I am also very worried.
Gabriele Otto
Fermilab Visual Media Services
precision measurements of particle
masses—both originated and first applied at Novosibirsk.
Our participation in the LHC project at CERN now
plays an especially important role in the future of Russian high energy physics. It is crucial for our physicists
to be full partners in these frontier experiments. But
under the current circumstances in Russia, it was almost
impossible for our
laboratories and institutes to obtain
additional funds to
contribute to the
LHC and participate
in designing and
building its detectors. Aided by the
wisdom and openmindedness
of
Carlo
Rubbia,
Chris LlewellynSmith, and our CERN colleagues, we found mutually
beneficial and affordable ways to permit this participation, which is now funded equally by CERN and the Russian government.
We in the Russian high-energy physics community
truly believe that international collaboration is the best
way to conduct our science in the future—not only for
Russia but for the world in general.
collaborating with Japanese physicists.
Meanwhile, Chinese and Italian physicists are proposing another cosmic-ray experiment
known as ARGO in the same place. Indeed, we are even
considering the possibility of establishing an international center for cosmic-ray physics experiments at Yangbajing; such a center would provide an ideal site for this
kind of research, attracting scientists from all over the
world.
Early in the next century, Chinese physicists will continue to make their due contribution in key experiments
in other countries. We are participating in the construction of both B factories and their experimental collaborations, and have joined both the CMS and ATLAS
collaborations at the LHC. Our participation will continue in experiments at the Tevatron and DAΦNE, as
well as at other laboratories. Chinese accelerator physicists are interested in collaborative R&D work on the
technology for future linear colliders. Other physicists
are interested in non-accelerator experiments such as
AMS and L3 Cosmics. The Chinese Academy of Sciences
strongly supports all these collaborations.
As a developing country, China’s contributions to international collaborations will however be rather limited during the next few decades. Therefore our physicists need to concentrate their resources and manpower
on key collaborations, make good contributions to these
projects, and become more visible. They should identify certain work that can be done in China, such as production of new materials, construction of subdetectors,
and developing software. By taking advantage of their
particular knowledge, plus the special techniques and
know-how of Chinese industries and materials sciences,
as well as our cheaper labor, our physicists can make
major contributions to these collaborations.
China has taken its place in the world in the realm
of science and technology. We are certain that during the
next century our country will make even greater contributions to the international community of high
energy physics.
A new electron cooling device for the Heavy Ion Synchrotron
being delivered to GSI in Darmstadt, Germany. The device
was developed and manufactured at the Budker INP.
(Courtesy GSI)
BEAM LINE
19
U.S. Collaboration on the LHC P
by GEORGE TRILLING
Forty-seven countries
and 299 institutions are
part of a team to build
the CERN Large Hadron
Collider and its detectors. This accelerator
will bring protons into
head-on collision at
much higher energies
than ever achieved. A
member of the U.S. collaboration, who has
been involved since its
beginnings, discusses its
history and participation
in this effort.
20
WINTER 1997
T
HE PUSH BY PARTICLE PHYSICISTS toward ever
higher particle beam energies is motivated by the fact
that much of the complexity observed at lower energies
may disappear when the energy becomes sufficiently high. Thus,
while beta radioactivity and electromagnetism have been separately known for 100 years, it is only in the last 30 years that new
accelerators have provided energies high enough to “unmask” the
fundamental relationship between the two phenomena. This is
because the basic force carriers involved in radioactivity, the W
and Z, are very massive, and can only be produced as identifiable
objects with particle beams of very high energy. By moving to yet
higher energies, particle physicists hope to unmask many more of
Nature’s hidden secrets, including the mechanism by which our
basic constituents acquire their masses. Their aspirations are currently focused on future experiments made possible by the Large
Hadron Collider (LHC) facility to be built over the next eight years.
The Large Hadron Collider is a proton-proton colliding-beam
facility to be housed in the Large Electron Positron Collider (LEP)
tunnel at CERN. Its design energy is 7 TeV per beam, a figure seven
times as large as the maximum Tevatron beam energy and seventy
times as large as the maximum LEP beam energy. The enormous
energy difference between the two colliders within the same
enclosure arises from the fact that LEP beam energies are limited
by the huge amount of electromagnetic radiation emitted by the
electrons traveling in circular orbits (a limitation that linear colliders such as the SLAC Linear Collider and the Next Linear Collider are designed to avoid). Circulating protons, by virtue of being
ogram
2000 times as heavy, emit relatively little radiation; in a tunnel of
fixed circumference, their energies are only limited by the magnetic fields achievable in practical superconducting accelerator
magnets (8.4T for LHC).
Up to the October 1993 cancellation of the U.S. Superconducting Supercollider (SSC) project, almost all U.S. groups interested in
pursuing physics at the “energy frontier” made accessible by the
LHC and SSC had been participants in one of two large SSC detector collaborations. By late 1993, the CERN management had
approved two largely European detector collaborations for the
LHC, ATLAS (A Toroidal LHC ApparatuS) and CMS (Compact
Muon Solenoid), to move to the preparation of technical proposals.
However the overall LHC project had not been formally approved
by the CERN Council because the available construction funding,
based largely on the ongoing CERN budget, was about 25 percent
short when summed over the proposed construction period.
In 1994 numerous U.S. groups, many of them previously
involved in SSC detectors, joined the ATLAS and CMS collaborations to pursue the energy-frontier physics that had been their
motivating scientific interest. Two additional detectors are
planned for the LHC: LHC-B optimized specifically for studying the
physics of B-meson decays, and ALICE aimed at the study of highenergy heavy-ion collisions. Since U.S. participation in LHC-B and
ALICE is currently small, and not included within the signed
agreements between CERN and the U.S. funding agencies, I shall
not discuss it here.
To overcome the funding shortfall, the CERN Director General,
Chris Llewellyn Smith, invited non-member-states (countries that
BEAM LINE
21
Countries Participating
in the LHC Program
Armenia
Australia
Austria
Azerbaijan Republic
Republic of Belarus
Belgium
Brazil
Bulgaria
Canada
People’s Republic of China
Croatia
Cyprus
Czech Republic
Denmark
Estonia
Finland
France
Republic of Georgia
Germany
Greece
Hungary
India
Israel
Italy
Japan
Kazakhstan
Korea
Latvia
Mexico
Morocco
Netherlands
Norway
Pakistan
Poland
Portugal
Romania
Russia
Slovak Republic
Slovenia
Spain
Sweden
Switzerland
Turkey
Ukraine
United Kingdom
United States of America
Uzbekistan
22
WINTER 1997
are not CERN member-states), whose physics communities had
substantial interest in exploiting the LHC, to participate financially and intellectually in the machine construction. This is a departure from tradition; in contrast to detector facilities, which are
built and funded internationally, accelerators are normally funded
by the host country or—as in the case of CERN—the host region.
The justifications for this departure, expressed from the point of
view of U.S. involvement, are the following: (1) The multi-billiondollar LHC stands at or beyond the limit of what a single region
can afford to fund. If such projects are to go forward, they need
interregional funding support, and such support is most naturally
sought from countries whose scientific communities have strong
interest in these projects; (2) The large U.S. community interested
in participating in LHC experiments, currently about 600 scientists
and engineers, has a strong stake in the timely completion of the
accelerator project. U.S. participation in the machine can help
ensure this timely completion; (3) Participation in the LHC
collider effort would afford new opportunities for the continuing
development of U.S. capabilities in the area of accelerators using
superconducting magnets.
The proposed U.S. participation in LHC was considered by the
1994 High Energy Physics Advisory Panel (HEPAP) Subpanel on
Vision for the Future of High-Energy Physics, under Sidney Drell’s
chairmanship, which gave a positive recommendation. Further
action by U.S. funding agencies awaited CERN Council approval of
the LHC project, which came in December 1994. To secure this
approval, CERN management presented a staged construction plan,
based solely on member-state contributions, that completed the
full LHC not earlier than 2008, with the expectation that, with adequate non-member-state support for the machine, the staging
might be avoided, and full completion achieved by 2004 or 2005.
Discussions between the Department of Energy (DOE), the
National Science Foundation (NSF), and the CERN leadership, relative to U.S. participation in the LHC program, were initiated in
April 1995. They culminated in the signing, on December 8, 1997,
by Energy Secretary Frederico Peña, NSF Director Neil Lane, CERN
Council President Luciano Maiani, and Director General
Llewellyn Smith of a Cooperation Agreement on the LHC
program. More detailed accelerator and experiments protocols
were signed later in December. These various agreements set out
the “rules” and funding levels under which the U.S. will participate in both LHC accelerator and detectors. The U.S. will commit
$250M from DOE and $81M from NSF for the ATLAS and CMS detectors, and $200M from DOE for the LHC accelerator. The totality
of NSF plus DOE detector funding is to be split about equally between ATLAS and CMS. The accelerator funding is to be split into
$90M for goods and supplies from U.S. industry, and $110M for systems and components provided by three national laboratories,
namely Brookhaven (BNL), Fermilab, and Lawrence Berkeley. This
accelerator collaboration is principally focused on the design, fabrication, and commissioning of elements for the LHC interaction
regions.
In light of the proposed U.S. and other non-member-state participation in the machine, the CERN Council, in December 1996, had
approved going forward on a non-staged LHC to be completed in
2005. Needless to say, Congressional approval of these funding
commitments was essential. In April, House Science Committee
Chair Sensenbrenner raised a number of concerns about the proposed U.S.-CERN agreements. To satisfy these, and with the approval of the CERN Council, the agreements were appropriately
modified. The full $35M request for DOE-supported LHC efforts in
fiscal year 1998 has been provided.
A
LTHOUGH THE U.S. HAS PREVIOUSLY participated
in detector projects abroad (L3, ZEUS, AMY etc.), such involvement has not yet occurred on the financial scale envisaged for LHC. Strong management is mandatory for the accelerator project and especially for the detectors, which involve
collaboration by large numbers of institutions. Each detector project
has a U.S. host laboratory (Fermilab for CMS and BNL for ATLAS) with
management oversight responsibility given to the host lab director
or his appointed representative. Because of the close coupling of DOE
and NSF in the detector projects, the two agencies are forming a Joint
Oversight Group (JOG) to oversee the detector fabrication efforts.
Each detector program will have a U.S. Project Manager reporting
to both the JOG and the host lab director.
BEAM LINE
23
Cutaway view of the ATLAS
detector. The inner detector,
calorimeters, and muon
detectors measure and identify
the various collision products.
Magnetic fields to deflect
charged particles are produced by a solenoid (for the
inner detector) and air-core
toroids (for the muon
detectors).(Courtesy Lawrence
Berkeley National Laboratory)
Solenoid
Magnet
Inner
Tracker
Hadron
Calorimeter
Electromagnetic
Calorimeter
Toroid
Magnets
Forward
Calorimeter
Muon
Detectors
Beam
Pipe
The physics goals of the ATLAS and CMS detector collaborations
are similar to those that motivated the SSC. While the design energy of 7 TeV per beam is one third of that for the SSC (but seven
times that of the Tevatron), the design luminosity of 1034 cm−2 sec−1
is ten times higher. These conditions place great demands on the detectors, in terms of performance and survivability in a hostile radiation environment. At full luminosity, each crossing of two proton
bunches will produce about 20 interactions, and these crossings will
occur every 25 billionth of a second. A whole range of opportunities for physics discovery will open up. These include the Higgs
boson or bosons, new spectroscopies such as supersymmetry, new
massive gauge bosons, and searches for evidence of compositeness
in what have heretofore been point particles. The Higgs sector is connected to the fundamental issue of how all our basic particles (quarks,
leptons, and gauge bosons) acquire their masses, and what determines
those masses. Recent work has shown that, if supersymmetry is
indeed found, the LHC experiments will be capable of numerous measurements to probe its details.
Computer simulations of searches for these phenomena have provided guidance to the design of detector subsystems. Such simulations, done for a sufficiently broad array of processes, give confidence
24
WINTER 1997
Forward
Calorimeter
Muon
Chambers
Tracker
Crystal
ECAL
Cutaway view of the CMS detector. The
tracker, calorimeters (including HCAL
and ECAL), and muon chambers are the
measurement elements for the various
outgoing particles. A large solenoid coil
produces a very strong magnetic field
for charged-particle momentum
measurement.
HCAL
y
z
x
Superconducting
Coil
Return
Yoke
that the ATLAS and CMS detectors can not only uncover what physicists are searching for (if it is there), but also discover unexpected and
entirely new phenomena if that is Nature’s way.
The main features of both detectors include: (1) high resolution
and highly segmented electromagnetic calorimetry to allow detection of the two-photon decay of a light Higgs boson (below 120 GeV);
(2) the ability to identify electrons and muons, and measure accurately their charges and momenta over a large angular range; (3) nearly hermetic hadronic calorimetry to measure hadronic energy flow
and detect missing momentum transverse to the beam line; (4) capability to identify the presence of a B-hadron decay through detection of a displaced vertex with high position-resolution silicon
pixel detectors; (5) operational capability, and survivability at the design luminosity of 1034 cm−2 sec−1.
With such capabilities, these instruments can determine, for each
proton-proton collision: the energies and directions of outgoing electrons, muons, photons, and jets; identify those jets originating from
bottom quarks; and measure the total transverse momentum associated with neutrinos or other undetectable neutrals. Furthermore
they can process enough of this information sufficiently quickly to
select, for permanent recording and detailed analysis, just the one
BEAM LINE
25
K. Shipp
Signing ceremony for the LHC
project on December 8, 1997, in
Washington, DC. Secretary of
Energy Federico Peña, left,
congratulates Luciano Maiani,
president of the CERN Council.
(Courtesy Department of
Energy)
collision in 100 million (still about 10 events/second) that may bear
the seeds of an important measurement or new discovery.
Since these detectors are intended to complement each other, their
similar design goals are accomplished in substantially different ways.
More detailed descriptions of some specific detector subsystems in
which U. S. groups have major responsibility are given by Gil
Gilchriese (ATLAS) and Dan Green (CMS) in the following articles
respectively.
Over the past few months, both detector collaborations have
submitted voluminous Technical Design Reports for most of their
detector subsystems, and these have undergone painstaking
review by the LHC Committee. The U.S. groups hope to have completed their DOE/NSF baselining reviews by early 1998. The scientific and technical challenges are enormous, but powerful international teams including a strong U.S. presence are very
effectively working together to meet those challenges. The future
looks exciting.
26
WINTER 1997
The ATLAS Inner Detector
by M. G. D. GILCHRIESE
The ATLAS experiment is being constructed by 1700
collaborators in
144 institutes
around the world.
It will study
proton-proton
interactions at
the Large Hadron
Collider at CERN.
The U.S. leader
of one of the major
systems describes
what it is like
working on the
inner tracking
detector.
A
GENERAL DESCRIPTION OF THE ATLAS detector is given in the previous article by
George Trilling. Twenty-eight U.S. universities and three national laboratories comprise about 20
percent of the ATLAS (A Toroidal LHC ApparatuS) col-
laboration, the largest single national group. U.S. physicists
are involved in essentially all aspects of the ATLAS experiment, but I will only describe here one area of activity—the
inner tracking detector.
Charged-particle tracking at the Large Hadron Collider (LHC) is
the most difficult technical challenge faced by the ATLAS and CMS
(Compact Muon Solenoid) experiments. There is now considerable
confidence that this challenge can be met by the proper mix of
technologies at an affordable cost. But a decade ago this was certainly not the general perception. I remember clearly sitting
behind a Nobel-prize-winning laboratory director at the 1986 Division of Particles and Fields Snowmass meeting during one of the
first presentations of studies of charged-particle tracking for the
Superconducting Super Collider (SSC). The then-laboratory
director wrote in his notebook: “Won’t work! Impossible!” And
this was at a modest luminosity of 1033 cm−2 sec−1 and not the 1034
cm−2 sec−1 we will face at the LHC! This succinct summary
BEAM LINE
27
Barrel SCT
Forward SCT
TRT
Pixel Detectors
The ATLAS Inner Tracking Detector
(approximate length 7 meters).
28
WINTER 1997
accurately reflected the uneasiness
of many people at that time. So what
happened to change this perception
and to give us confidence now that
even 1034 cm−2 sec−1 may not be the
ultimate limit at which charged particle tracking is possible?
The essential change in the last
decade has been to realize that it is
possible to build tracking detectors
with very, very many independent
elements (the ATLAS tracking system
will have over 108 such elements)
that can each have a time resolution
of a few nanoseconds or better. And
that this can be done for an affordable cost (although just barely) and
with the ability to survive the hostile
radiation environment at the LHC.
Our ability to make these optimistic statements follows from a
decade of intense research and development on tracking detectors. A
focused program of detector R&D for
the SSC began in 1986 and shortly
thereafter independently in Europe
for the LHC. The results of these R&D
programs appear today to be even
more successful than the original
proponents imagined. The design of
the ATLAS inner tracking detector
follows directly from these worldwide R&D efforts.
The ATLAS Inner Detector is
shown above. It consists of three different tracking technologies. At the
outer radii, there are about 400,000
straw tube drift cells that, in addition
to their charged-particle tracking
function, are used to detect transition radiation X-rays from electrons
(therefore named the Transition Radiation Tracker or TRT). At the intermediate radii, there is a large area
(60 m2) silicon strip detector (about
5 million individual channels). For
historical reasons this is called the
Semiconductor Tracker or SCT. And
closest to the interaction point there
is about 2 m2 of silicon pixel detectors with 1.5× 108 individual elements—pixels.
The innermost radius of each of
these types of detectors is determined
by either their ability to function at
the LHC luminosity of 1034 (in the
case of the TRT) or by their ability to
survive about ten years of operation
(in the case of the silicon-based
detectors). In fact, the innermost
pixel system layer, which is critical
to the ability to identify particles
containing the b-quark, will last only
about one year at 1034cm−2sec−1. It
will be replaced periodically unless a
more radiation-tolerant solution is
found. The outermost radius of each
type of detector is set in part by performance requirements (for example,
momentum resolution) but is even
more strongly influenced by the need
to keep costs within affordable
bounds, not just for the inner tracking
detectors but for the entire detector.
The components of the inner
tracking detector will be built all over
the world and shipped to CERN for
final assembly and installation.
There are about 60 different institutions involved, which is more
institutions than even the largest collaboration for an operating experiment in the United States. This
“United Nations” approach to
detector design and construction
does have its strengths and weaknesses. The primary strength is that
the available technical expertise is
very substantial and it is therefore
possible, in principle, to understand
every detail in depth. The principal,
and inevitable, weakness is that this
Roy Kaltschmidt, LBNL
expertise is dispersed all over the
planet and, as a result, it becomes difficult to reach decisions and to
achieve the concentration of effort
that is necessary in a complicated
and long technical project. That all
of this (usually) works is a reflection
of the intense desire of the physicists
in each institution and country to
“make it work” and ultimately to
build the best experiment.
The U.S. collaborators are working on all three parts of the ATLAS inner tracking detector. Duke University, Indiana University, and the
University of Pennsylvania did pioneering work in the development of
straw tubes for the SDC detector for
the SSC. Duke, Indiana, Hampton
University, Norfolk State University, and the University of Pennsylvania are now responsible for the barrel part of the Transition Radiator
Tracker and a substantial fraction of
the TRT electronics. Modules that
make up the barrel TRT will be assembled and tested by Duke, Indiana, Hampton, and Norfolk and then
shipped to CERN for final assembly.
Some of the parts needed for these
modules will be made in the United
States and others in Europe, including Russia. The University of Pennsylvania, having specialized in the
design of integrated circuits and other electronics for the TRT, will fabricate and test these components and
then ship them to module assembly sites in both the U.S. and in Europe. This type of exchange of components from the U.S. to Europe, and
vice versa, is typical of almost all
parts of the ATLAS detector. It is determined by the availability of local expertise both within the high energy physics community and within
industries in a specific country and
the desire to minimize costs by
realizing economies of scale.
Another, even more diverse, example of this type of interchange of
components and expertise is in the
fabrication of the silicon strip modules for the Semiconductor Tracker.
A module consists of silicon detectors, the integrated-circuit-readout
electronics that are mounted on
these detectors, and the electromechanical parts that support and
cool the module and connect it to external electronics. About 4100 such
modules are needed, which represent
more than an order of magnitude increase in scale over existing silicon
detectors. In addition, the many institutions involved are located from
Australia to Russia, making it possible to accumulate the financial
resources required but in so doing
creating a substantial organizational
challenge.
There will be seven regional
centers for assembly of modules,
with components coming from
even more places. The United States
is one regional center, with mod-
From left to right, John Richardson,
(LBNL); Julio Bahilo-Lozano (Spain);
Leif Ericson (Sweden), and Roberto
Marchesini (Italy) are working at
Lawrence Berkeley National Laboratory
on pixel and semiconductor tracker
detector prototypes.
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29
The essential change
in the last decade
has been to realize
ules and related electronics being
designed, assembled, and tested by
Lawrence Berkeley National Laboratory ( LBNL ), the Universities of
California at Irvine and Santa Cruz,
and the University of Wisconsin.
The U.S.-built modules will be assembled and tested at LBNL and UC
Santa Cruz, then shipped to England for placement on a supporting
structure. UC Irvine and Wisconsin have the primary responsibility
for the design and fabrication of
electronics that reside outside the
detector, in fact outside the ATLAS
underground hall, and which are
connected by fiber optics to the
SCT modules.
The pixel system is located closest to the interaction point. There are
two reasons why silicon pixel detectors are needed at the LHC. First,
the intense radiation environment of
the LHC, especially at small radii,
damages silicon detectors. At some
point, the damage reduces the signal
induced by the passage of a charged
particle so much that the fast electronics used, for example by the SCT,
cannot sense the charge with good
efficiency above the intrinsic noise
that is inherent to the system. The
trick in the case of a pixel detector is
to reduce the noise by reducing the
input capacitance seen by the electronics, which means reducing the
size of the individual silicon sensing
areas from 12 cm ×80 microns in the
case of the SCT modules to 300 microns × 50 microns in the case of the
pixel detector. As a consequence, the
pixel electronics must be mounted
directly on top of the silicon sensing
elements, and thus the ATLAS pixel
detector contains about 2 m 2 of
integrated circuits, a large fraction of
30
WINTER 1997
that it is possible
to build tracking
detectors with very
many independent
elements that can
each have a time
resolution of a few
nanoseconds or better.
And that this can
be done for an
affordable cost and
with the ability
to survive the hostile
radiation environment
at the LHC.
the integrated circuits needed for the
whole experiment. The LHC interaction rate and radiation environment are such that CCD pixel detectors, such as those so successfully
used in the SLAC Large Detector at
the Stanford Linear Collider, cannot
be considered. The second need for
pixel detectors is driven by the high
density of tracks in hadronic jets at
the LHC and the desire to find particle tracks within these jets for tagging particles containing the b-quark
as well as for other reasons. The enormous granularity of the pixel detector, located near the interaction point
where the track density is highest,
greatly improves the track finding
capability.
The U.S. institutions working on
the ATLAS pixel detector are LBNL,
UC Irvine, UC Santa Cruz, University of New Mexico, University of
Oklahoma, SUNY Albany, and the
University of Wisconsin. Irvine and
Wisconsin are responsible for the offdetector electronics, which are similar to those used for the SCT. The
other groups are working on all
aspects of the pixel detector—
integrated circuit electronics, silicon
detectors, module construction and
mechanics—and will be responsible
for delivering the forward/backward
disk elements of the pixel system for
the experiment.
The construction phase of the
subelements of the ATLAS Inner
Detector has started. The TRT has
entered this phase, to be followed by
the SCT next year and then the pixel
detector a year later. It has taken
more than a decade of R&D involving almost all of the major countries
in the high energy physics world to
get to this stage. Although the final
proof awaits the turn-on of the LHC,
it appears now that this long effort
has been spectacularly successful. In
this sense, the ATLAS inner tracking
detector is an example of the best
of international collaboration in high
energy physics.
The CMS Hadron Calorimeter
by DAN GREEN
The CMS experiment will use a large general
purpose detector to study proton-proton
interactions at CERN’s Large Hadron Collider.
A major subsystem, the hadron calorimeter,
will measure the energy flow in these interactions.
To be realistic today is to be a visionary—Hubert Humphrey
White House Conference on International Cooperation
T
HE COMPACT MUON SOLENOID (CMS)
collaboration consists of about 1650 high-energy
physicists from 150 institutions scattered around
the globe whose collective goal is to take the next
discovery step at the “energy frontier.” The U.S.
part of this collaboration, which formed in response to the
1993 demise of the Superconducting Super Collider, includes
about 300 physicists from 40 institutions. Our challenge is to
participate successfully in what are arguably the first truly
global scientific experiments.
The CMS detector is a general purpose detector. When
voyaging into the unknown, it is best to be ready for anything. In the case of CMS, where we do not know exactly
what we will find, we must be prepared by building a detector capable of measuring all the known fundamental particles to good accuracy.
The particles of matter are categorized as leptons and
quarks. The fundamental force carriers are the photon of
electromagnetism; the weak force carriers, W and Z; and the
strong force carriers, the gluons. Quarks interact strongly
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31
W. Wu
Dan Green, left, and Prof. Xuan Zhu
of the Chinese Academy of
Sciences discuss potential
collaboration on CMS between the
United States and Chinese groups.
32
WINTER 1997
and thus evolve into hadrons—
strongly interacting particles such as
the pion and proton. The leptons are
either charged or neutral. The neutral leptons, called neutrinos, interact so weakly that they
escape direct
detection. At
every moment, for example, billions of solar
neutrinos are
trav e r s i n g
our bodies
without our
notice and without causing us harm.
We infer the production of neutrinos
in a reaction by the energy that they
carry off undetected, which shows
up in the detector as an imbalance in
the momentum. Since particle detection is extremely difficult at small
angles to the incoming beams, only
the energy imbalance transverse to
the beams can be measured.
The CMS detector is organized into
specialized subdetectors. I will concentrate on the hadron calorimeter—
referred to by George Trilling as
“nearly hermetic”—in part because
U.S. groups have a major role in designing and building it. The purpose
of this calorimeter is to measure the
energies and directions of all strongly interacting particles —the quarks
and gluons—produced in an interaction. The term “hermetic” means
that nearly all secondary particles are
observed. If this is true, then missing transverse energy in the final
state implies the production of a noninteracting particle. Therefore, the
detectors must be fully active, without “dead” or inactive regions.
The objects actually observed are
not the fundamental particles themselves, which are hidden from our
view, but “jets” of ordinary particles.
These ensembles of hadrons are emitted as a tightly collimated spray with
almost the same direction and energy as the parent quark or gluon. It is
these jets which are detected in the
calorimeter subsystem. A highenergy jet might attain an energy of
1 trillion electron volts (1 TeV). That
energy is 40 billionths of a calorie;
therefore, we cannot simply measure
the temperature rise in the calorimeter because it is infinitesimal.
The method we use is to convert
the energy to mass, à la Einstein, and
thus to produce many secondary particles. These particles, in turn, produce tertiary particles. In a fashion
analogous to the geometric growth
of bacteria, the number of particles
in the calorimeter increases rapidly
in a cascade of interactions until the
“food”—in this case the energy needed to produce new particles—runs
out. At that point, multiplication
stops. The particles in turn ionize the
active detecting medium, and the resultant rapid pulse of deposited energy is measured. Since the number
of produced particles is proportional
to the incident energy, E, what
amounts to counting these particles
gives us a measure of the energy.
The statistical fluctuations in the
number of particles produced means
that the fractional energy error, dE/E,
is proportional to 1/√E. Note that the
performance improves with energy,
which explains why calorimetry
becomes an important tool in highenergy experiments. To be fair, any
nonuniformity of manufacturing or
performance has the result that the
The tile and wavelength-shifting fiber
active elements of the hadron
calorimeter detector for CMS. (Courtesy
Fermilab Visual Media Services)
mean energy measured in different
parts of the detector varies. This effect causes an error, dE/E, that goes
as a constant and thus dominates the
high-energy behavior of the detector.
It is this error that the CMS calorimeter group has worked to reduce to
as low a value as possible.
The groups who are working to
design and build the CMS hadron
calorimeter (HCAL) come from
China, Hungary, India, Italy, Russia
and Dubna member states, Spain,
Turkey, and the United States. Over
the past four years we have formed a
team with the goal of not only designing and building it, but also installing it in CMS during 2003 and
2004, and using it for physics beginning in 2005. The diversity and geography of the hadron calorimeter
groups requires special effort to unify the team. Once the design is complete, it must be tested in beams of
particles, and the ones most accessible to all the HCAL groups are at
CERN in Geneva, Switzerland. The
planning, execution, and analysis of
these test beam runs amount to a
small international experiment in itself, and it is an enviable accomplishment that the HCAL groups
have run every year since 1994.
The calorimeter itself is deployed
in five distinct pieces: a barrel at
wide angles to the incident beams;
two endcaps at intermediate angles;
and two forward detectors at small
angles. These pieces are the responsibility of different subgroups.
The hadron calorimeter is immersed in a 40 kG magnetic field,
which is used to deflect charged particles and thus measure their
momentum in other CMS subsystems. As a consequence, HCAL must
be built of nonmagnetic materials, such as copper.
As a result of concerted efforts, the
HCAL community
has adopted many
solutions in common such as the
optics and transducers in the barrel
and the two endcaps. Because the
forward detector
system is exposed
to high radiation, it
requires different
solutions; however,
we have adopted a
common front-end
electronics and a common readout
system for all of HCAL which will
simplify the work of building and
commissioning it.
As seen above, we have achieved
an almost hermetic design. The active element is a scintillator tile
which emits light in the blue. That
light is absorbed and shifted to the
green by a wavelength shifting (WLS)
fiber rather than a conventional light
pipe. By using a WLS to “cool” the
scintillator light, we can reduce the
dead area dramatically, leading to the
required performance.
The search for the origin of mass,
which is the primary goal of LHC experimentation, requires the study of
rare processes. Thus, very high beam
fluxes are needed, which means that
the hadron calorimeter must endure
unprecedented radiation doses. In the
barrel and endcaps, scintillator will
continue to function; however, the
forward detectors will be exposed to
up to 1 billion rads, and a different
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33
The CMS prototype hybrid photodetector (top) and a schematic of the pixel
readout (bottom). This device functions
in the 40 kG field of CMS where a conventional phototube cannot. (Courtesy
Fermilab Visual Media Services)
34
WINTER 1997
technology is needed. To compare
it to everyday life, we all absorb a
yearly dose of 0.2 rads from cosmic
rays, and a dose of 300 rads is lethal.
Because the dose of the forward detectors is high, their optics are made
out of pure quartz, which is also used
for reactor windows.
In the 40 kG field of CMS, conventional transducers, such as photomultiplier tubes,will not function,
so the HCAL community has found
and tested other technologies. The
device shown on this page is a new
hybrid combining a normal photocathode with a silicon diode acting
as the anode. The resulting signals
must be compactly processed and
sent off the HCAL detector to remote
counting rooms. In this case, we
adopted the solutions of the telecommunications industry and converted
the digitized signals back to light for
transmission along fiber optic cables.
These solutions are again chosen to
maintain the hermetic character of
HCAL.
The dispersed HCAL community
is doing its work more or less in concert using new computing and networking technologies such as electronic mail, teleconferencing, and the
World Wide Web. For example, we
assembled a 530-page Technical
Design Report using everyone’s input—which is nothing unusual—but
in the process, a “virus” was picked
up. After some frantic efforts, it was
finally eradicated.
In the future, global efforts will
become the norm as we ask deeper
questions and thus attack harder
problems. As the introductory quote
illustrates, this is a practical fact of
our scientific life. It is the science
that is our pole star, and it guides
us toward a global community. Indeed, the rewards go beyond science.
The personal pleasures of meeting
and working together with scientists
from many cultures make all the
challenges stimulating and ultimately even satisfying.
International Collaboration
on Linear Collider Research
and Development
by GREGORY LOEW & MICHAEL RIORDAN
Physicists around the globe are cooperating
on designs for a trillion-volt linear collider.
S
INCE THE MID-1980s a growing international collabora-
tion of high energy physics laboratories and other institutions
has been doing extensive research and development toward the
design and construction of a TeV-scale linear electron-positron collider.
The particle physics community has been interested for years in building such a collider, which would fire tiny bunches of electrons and
positrons at each other with combined energies between 0.5 and 1.5
trillion electron volts. This interest intensified with the recent decision by the European Laboratory for Particle Physics (CERN) to proceed
with the Large Hadron Collider. Indeed, these two machines can make
highly complementary contributions to our understanding of elementary particles.
Such a TeV linear collider can serve many functions. It will be a precision tool to study production and decays of the massive top quark. If the
Higgs boson (or bosons) and supersymmetric particles exist, it should be instrumental in fostering their discovery and further study. If they do not, such
a collider will allow the exploration of other mechanisms being proposed for
electroweak symmetry breaking, which is thought to imbue elementary particles with their widely differing masses. These are several of the burning
physics questions that need to be elucidated during the coming decade.
In addition, a TeV linear collider will provide exciting physics research
opportunities based on high energy electron-electron, electron-photon and
photon-photon collisions. Other applications, such as free-electron lasers for
the study of matter at atomic dimensions, are also possible.
BEAM LINE
35
M
OTIVATED BY the late
1980s startup of the SLAC
Tsumoru Shintake and David Burke
with the laser beam monitor built by KEK
for the Final Focus Test Beam at SLAC.
36
WINTER 1997
Linear Collider and the
possiblity of extending this technology to higher energies, a nucleus of
institutions began doing collaborative R&D in this field. At first, this
effort was fairly informal, resulting
in small one-on-one joint investigations. During the 1990s, it gradually
evolved into larger projects such as
the 300 meter Final Focus Test Beam
at the Stanford Linear Accelerator
Center. The principal goal of this
roughly $20 million project was to
study the design and operation of a
state-of-the-art magnet array required
to generate the exceedingly narrow,
ribbon-like electron and positron
beams needed at the interaction
point of a TeV linear collider.
Groups from the German Electron
Synchrotron (DESY) in Hamburg; the
Max Planck Institute in Munich; the
Linear Accelerator Laboratory (LAL)
in France; the National Laboratory
for High Energy Physics (KEK) in
Japan; the Budker Institute of Nuclear Physics (BINP) in Novosibirsk,
Russia; the Fermi National Accelerator Laboratory in Batavia, Illinois; and
SLAC joined forces to build this facility. The Russians fabricated almost all
of the forty precision dipole, quadrupole, and sextupole magnets that
serve as “optical” elements in what
is essentially the world’s biggest
“compound lens.” The last two quadrupoles, which were manufactured
by Japanese industry under the direction of KEK physicists, have pole
faces machined to micron accuracies.
DESY physicists supplied a highprecision alignment system to guarantee that components of this complex magnet array remain in their
designated positions. And KEK and
LAL built monitors to measure the
transverse dimensions of the electron bunches at the focal point—one
based on Compton scattering of photons (see photograph at left) and the
other on ions scattered from gas jets.
Experiments at SLAC have produced electron beams that are only
120 nanometers high (a typical virus
is about 100 nm across), in good
agreement with predictions. That’s
an extraordinary vertical compression factor of over 300 on the initial
50 GeV beam supplied by the SLAC
linear accelerator. This level of demagnification already exceeds what
is required for TeV linear colliders.
What’s more, the Final Focus Test
Beam has demonstrated that such
flat, narrow beams can indeed be controlled and monitored, which was
not at all obvious when this project
began construction.
The diversity of projects
and test facilities we
have created somewhat
I
N EARLY 1987, at a meeting of
the International Committee on
Future Accelerators (ICFA), SLAC
Director Burton Richter had suggested that all groups doing research
on linear colliders start working together more cohesively. In 1988 the
community began holding two series
of regular workshops around the
world—one (labeled “LC”) to review
and compare the various design alternatives for a large linear collider,
and the other to discuss the physics
potential of such a machine. During
LC93 at Stanford, DESY, KEK, and
SLAC exchanged an informal memorandum of understanding to establish an international collaboration
whose main purpose was to pursue
linear collider R&D cooperatively.
The collaboration’s primary objectives, according to David Burke and
Richter, was “to enhance the exchange of personnel between participating institutions, to promote
coordination in planning and sharing
of research facilities, and to provide
a mechanism for all interested parties to participate in the evaluation
of the alternative technological approaches that are presently being
pursued.”
That agreement established a Collaboration Council, whose first formal meeting occurred in July 1994 at
the European Particle Accelerator
Conference in London. The Council,
in turn, set up a Technical Review
Committee (TRC) whose specific
charge was to examine and compare
the various accelerator technologies
and designs that might be suitable
for a linear collider with an initial
center-of-mass energy of 500 GeV and
a luminosity in excess of 1033cm−2
sec−1, which could be expanded to at
spontaneously throughout
the world community
is producing a broad body
of knowledge that benefits
all of the projects.
least 1 TeV with roughly five times
higher luminosity.
The TRC consisted of more than
50 scientists from 17 institutions
around the globe. Meeting and corresponding over the following year
and a half, they produced and published a comprehensive R&D report
that was distributed to the community in January 1996. This document presents descriptions of all
linear-collider designs so far proposed, comparative reviews of major
subsystems, descriptions of relevant
test facilities and experiments done
on them, plus the potential of the
various designs for being upgraded
to higher energies. The report lists
present and possible future areas
of collaboration. It concludes that
“the diversity of projects and test facilities we have created somewhat
spontaneously throughout the world
community is a good hedge against
mistakes, and . . . it is producing a
broad body of knowledge that benefits all of the projects.” The TRC report is available on the World Wide
Web at www.slac.stanford. edu/xorg/
ilc-trc/ilc-trchome.html; essential
parts of it, including progress reports
and tables of major linear-collider
design parameters are updated about
twice a year.
A
FTER NEARLY a decade of
international collaboration
on linear collider R&D,
where does the community stand
today? Five major new test facilities have recently begun operation.
These include two model test accelerators at DESY, one each at SLAC
and CERN, plus an advanced storagering facility at KEK whose goal is to
study the preparation of narrow,
ribbon-like beams to be injected into
such linacs. As a result of this and
other research, the status of the four
principal categories of linear-collider
designs (see top table on page 38) is
becoming better understood.
Although the parameters and
technologies of the main linacs in
these design categories differ substantially (see bottom table on page
38), the machines share many common features and problems. To reach
the desired luminosity, for example,
all approaches (except the Russian
VLEPP design) accelerate many electron or positron bunches in each
pulse of microwave radiation. But
launching such long sequences of
closely spaced bunches means that
the electromagnetic fields generated
in the wake of each bunch—its socalled wakefields—can deflect the
following bunches up, down, or sideways. This troublesome effect can
make it difficult to maintain the extremely narrow, flat electron and
positron beams needed at the interaction point to attain high collision
rates. Thus all linear-collider designs
(except VLEPP) use techniques to
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37
Linear Collider World Picture
Collider
Design
“Hub”
Laboratories
Corresponding
Test Facilities
TESLA
DESY
TESLA Test Facility
SBLC
JLC(C)
DESY
KEK
S-Band Test Facility
Microwave Systems
JLC(X)
NLC(X)
VLEPP(J)
KEK
SLAC
LBNL, LLNL
BINP
CLIC
CERN
Accelerator Test Facility
SLC, FFTB, NLC Test Accelerator
Relativistic Two-Accelerator Test Facility
VLEPP Test Facility
CLIC Test Facility
Parameters for a Linear Collider with a Total Energy of 500 GeV
TESLA
SBLC
JLC(C)
JLC(X)
NLC
VLEPP
CLIC
Main linac
frequency (GHz)
1.3
3
5.6
11.4
11.4
14
30
Luminosity
(cm−2s−1) × 1033
6
5.3
7.2
6.1
5.3
9.7
4.9
38
30
8.6
6.2
12.2
8
10.8
Accelerating
Gradient
(MV/m)
25
17
33
56
55
78
100
Number of
klystrons
616
2517
4184
4400
3030
1400
2 drive linacs
5650
16650
7200
12750
9720
300
30,000
Beam height
at final focusa
(nm)
Number of
bunches/second
beam height given here is twice the rms vertical beam dimension σy* generally quoted
in technical literature.
aThe
38
WINTER 1997
Possible Future
Interaction
Point
“Dog-bone”
Damping Ring
Bunch
Compressor
Positron
Main Linac
e+
PreAccelerator
Auxiliary
Positron Source
e+
Positron
Target
Bunch
Compressor
Electron
Main Linac
e–
Electron
Source
e–
Interaction
Point
PreAccelerator
Positron
Beam Dump
Wiggler
Magnet
Electron
Beam Dump
33 kilometers
suppress these wakefields before they
cause serious damage to beam quality.
Other features common to all
four design categories include particle injectors; damping rings; alignment systems; ground-vibration suppressors; vacuum systems; feedback,
instrumentation and control systems; beam delivery systems; and
final-focus systems—as well as
much of the civil engineering and
electromechanical infrastructure. In
all of these areas, valuable crossfertilization and collaboration occurs among the various groups,
which benefit from reviews that
take place at the regularly scheduled
LC workshops.
H
EADQUARTERED AT
DESY, the TESLA collaboration involves 22 institutions
spanning the globe from Beijing
through Warsaw and Paris all the
way to Los Angeles. This team has
designed the only machine that uses
superconducting accelerating cavities for the main linacs (see diagram
above). With microwave power at
1.3 GHz accelerating 5650 bunches
per second, it has the greatest time
lag between bunches (708 nanoseconds), the lowest transverse wakefields and thus the loosest alignment
tolerances. Other special features
include a long “dog-bone” shaped
damping ring and a positron-
production system that uses gamma
rays generated by passing the primary
electron beam through a wiggler
magnet.
The new TESLA Test Facility is being assembled in successive steps
through the addition of cryomodules
that contain the superconducting
cavities. It has already generated a
125 MeV electron beam, and in the
next few years it will be extended
to incorporate a free-electron laser.
Physicists and engineers building this
test facility have so far achieved an
accelerating gradient of 16 million
volts per meter (or 16 MV/m) and are
making good progress toward their
design goal of 25 MV/m. Their greatest challenge is to develop techniques
to turn these encouraging results into
a reliable and affordable technology.
The S-band Linear Collider (SBLC)
proposed by DESY physicists as a
TESLA backup takes advantage of the
most widespread and proven microwave technology—the 3 GHz S-band
technology used for decades at Stanford and elsewhere. Taken together,
its two “conventional” linacs are
roughly equivalent to ten SLAC
linacs and would stretch about 30
kilometers in all. After TESLA, the
SBLC has the next-largest beam
height at the final focus. It would
operate at 50 microwave pulses per
second with 333 bunches per pulse
spaced 6 nanoseconds apart. Because
Layout of the proposed TESLA linear
collider, which employs superconducting accelerating cavities in both main
linacs.
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39
KEK and SLAC physicists who recently
performed experiments at KEK’s
Accelerator Test Facility.
40
WINTER 1997
of this multibunch operation, its accelerating structures have been designed to detune and damp most
transverse wakefields by using two
sets of higher-order mode couplers in
each section whose signals can also
be used for alignment purposes. Initial tolerances are about 100 microns,
and the sections must eventually be
aligned to within 30 microns. Prototypes of the 150 megawatt (peak
power) klystrons needed by the SBLC
have been developed at SLAC as part
of a bilateral collaboration with DESY.
In the original TRC report, the
C -band Japan Linear Collider, or
JLC(C), was not considered in detail
because experimental work on it at
KEK had not yet begun. Since then an
active R&D program has been started on its microwave components, including a 50 megawatt klystron and
an ingenious 1.8 m accelerator structure that lets the undesirable transverse wakefields leak out while keeping the longitudinal, accelerating
mode “choked” inside the cavity.
This choke-mode structure eliminates wakefield problems and has an
alignment tolerance of 30 microns.
The JLC(C) beam characteristics are
similar to those of the X-band designs
(see below), except for a longer bunch
length.
The X-band Japan Linear Collider,
or JLC(X), and the SLAC-designed
Next Linear Collider, or NLC, both
use 11.4 GHz microwave power for
their main linacs. They have similar
pulse repetition rates, numbers of
bunches per pulse, particles per
bunch, and peak luminosities. The
different beam heights at the interaction point do not arise from any
fundamental design differences. As
the cooperation between KEK and
SLAC matures, this and other remaining differences will likely shrink
—a process that has already occurred
in the design of the accelerator structures. The NLC currently uses accelerator sections in which transverse wakefields are detuned and
damped by coupling these modes to
external manifolds and loads. The
latest sections of this type have been
machined at Lawrence Livermore
National Laboratory (LLNL), cleaned
at SLAC, diffusion bonded in Japan,
and returned to SLAC for final brazing. Tests of these sections have begun on the Next Linear Collider Test
Accelerator facility at SLAC (see photograph on the next page).
Microwave power for the NLC
will be supplied by 75 megawatt Xband klystrons that use permanent
magnets to focus the stream of lowenergy electrons traveling through
each klystron tube. This energysaving innovation has recently been
successfully tested at SLAC. Similar klystrons will likely be used in
the JLC(X) design. To increase the
peak power levels, both machines
will probably use the delay-line distribution system proposed by KEK
physicists to combine the microwave
pulses from several klystrons and
distribute slices of the resulting pulse
to individual accelerator sections.
Because much of the cost of these
X-band collider designs comes in the
manufacture of their klystrons and
the modulators that supply them
with electrical power, there are
substantial R&D efforts under way
to reduce these costs and attain high
power-conversion efficiency.
The trains of electron bunches for
both machines will be generated by
laser beams impinging on photocathodes, and the positron bunches
by improved versions of the positron
source now used on the SLC. After
initial acceleration to about 2 GeV
by various L-band and S-band preaccelerators, these bunches will be
compressed by a factor of 100 in
height and 10 times in width by circulating them for several milliseconds in damping rings. A full-scale
prototype of such a damping ring is
now being tested at KEK’s Accelerator
Test Facility (see photos on pages 16,
18 , and opposite) where scientists
from Japan, Europe, and the United
States are performing joint experiments and making good progress.
Seven Russian institutions have
been collaborating on the VLEPP
design with physicists from Finland
to Japan. This machine would accelerate only a single bunch of electrons or positrons in each microwave
pulse, thus eliminating the wakefield
problems of the multibunch designs.
But VLEPP must achieve its high
luminosity by cramming about
twenty times more particles into
each bunch, which leads to higher
backgrounds when the bunches collide at the interaction point. Although the VLEPP project is on hold
because of lack of funding, BINP
scientists continue to make important contributions by performing
specialized microwave and other
studies at home and abroad.
The JLC, NLC, and VLEPP linacs
can be upgraded in energy by increasing their active length and/or
adding microwave power. Another
approach to boosting the NLC energy is being explored by groups at the
Lawrence Berkeley and Livermore
National Laboratories; this involves
the use of a parallel 10 MeV “drive
beam” accelerated in an induction
linac to generate the microwave power. If successful, such a two-beam
technology may replace klystrons in
the next decade or two.
The CERN, or Compact, Linear
Collider (CLIC) involves a dozen
institutions, mainly from Europe but
also including the U.S. and Japan, that
are combining their R&D efforts on
another two-beam accelerating technology that has been pioneered by
CERN. This unique machine would
operate at the highest microwave frequency, 30 GHz, and have potentially
the highest accelerating gradient. But
it also has the strongest wakefields,
and therefore the tightest fabrication
and alignment tolerances, and it
requires a number of innovations.
Accelerated by LEP-style superconducting cavities, a very intense 3 GeV
Juwen Wang, Ted Lavine, and Chris
Adolphsen with the Next Linear Collider
Test Accelerator.
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41
Drive Beam
Main Beam
Transfer Structures
Accelerator Structure
drive beam induces microwave
pulses in transfer structures that
transmit these pulses over to the
main linac (see illustration above),
where they boost bunches of
electrons or positrons to their ultimate energies. The challenge of manufacturing thousands of klystrons,
modulators and microwave pulse
compressors is replaced by the need
to develop two high-current beams
that can generate high-frequency
pulses of the required square-wave
shape.
One advantage of the CLIC
scheme is that most of the components can be housed in a single tunnel, thus lowering conventional construction costs. But certain features
of the drive and main beams remain
to be determined—particularly for
operation at 60 particle bunches per
microwave pulse, which is needed to
raise the luminosity to the level of
the other designs. These questions
will be examined in experiments on
the CLIC Test Facility, a 30 m long
accelerator that began operation at
CERN in 1995 and is now undergoing
a major upgrade.
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H
AVING READ thus far,
you may well wonder
whether this entire effort is
a collaboration, or an intense global
competition. Such a reaction would
not be totally unwarranted. Although
they all share similar problems,
TESLA, the “conventional” microwave machines, and CLIC are very different designs. As it seems unlikely,
and is probably undesirable, for the
world to build more than one TeV linear collider, you may well ask, “How
will the present situation unfold?”
In attempting to answer this question, we can only speculate. The
linear-collider community has recently bifurcated into two distinct
coalitions. KEK, SLAC, and other institutions interested in X-band colliders are gradually joining forces to
work toward a single design. DESY
and its collaborators are focusing on
the superconducting TESLA approach, with SBLC as a backup. These
two coalitions intend to prepare conceptual design reports—including
complete engineering studies and
cost estimates—by the turn of the
century. The CLIC program will
A section of the proposed CLIC twobeam accelerator. An intense, lowenergy drive beam generates
microwave pulses that accelerate
electrons or positrons in the main linac.
continue doing R&D until 1999 and
then undergo a broad review to determine how to proceed. Since this
two-beam technology offers potential accelerating gradients above 100
MV/m, a design based on it may
eventually lead to a third-generation
linear collider operating at 1–3 TeV.
From all these efforts, it should
be possible to draw some useful and
fairly definitive comparisons. Whatever is learned, we hope that countries interested in working on a linear electron-positron collider will
eventually join forces and jump on
the best bandwagon. In the past,
however, a serious obstacle to building an accelerator or collider internationally was the difficulty of agreeing on a single site.
This difficulty is not scientific,
nor is it rooted in nationalism—or at
least it shouldn’t be. Physicists have
stood at the forefront of the global
movement toward internationalism;
they have extensive experience working together on common projects.
The difficulty is mainly cultural:
where to live, what food to eat, what
coffee shop to frequent, what language to speak at the supermarket,
where the children go to school.
CERN solved this knotty problem
many years ago, but in the midst of
a relatively homogeneous European
culture. The next—and truly international—leap will be substantially
greater. Perhaps the resolution lies
in the extensive use of jet planes and
high-speed computer networks. To
some extent, it should be possible for
many—but not all—collaborators to
remain situated around the globe and
still make important contributions
to an international linear collider.
THE UNIVERSE AT LARGE
What, and Why, is the International
Astronomical Union?
by VIRGINIA TRIMBLE
“. . .it is desirable that the
nations at war with the Central
Powers withdraw from the
existing conventions relating
to International Scientific
Associations. . .as soon as
E
RATOSTHENES (something BC) is supposed to have
measured the circumference of the earth by noting that the
sun, which cast a seven degree shadow at Alexandria, si-
multaneously shone straight down a vertical well at Cyrene. We
suspect he must have had a long-distance collaborator.* Moving
briskly through the Middle Ages and out the other end, we find
Kepler in Prague using observations by Tycho Brahe of Denmark
to trace out the laws of planetary motion, Galle in Berlin discover-
circumstances permit. . .and
ing Neptune on the basis of calculations made by Leverrier in
that new associations, deemed
France, and so forth.
to be useful to the progress
of science and its applications,
be established without delay
Indeed, many of the uses and aims of astronomy absolutely demand
world-wide cooperation. Unless everybody has the same, accurate,
almanacs and clocks that keep the same time, you are likely to find your
ship in St. Paul’s Cathedral rather than the English Channel or your radio
telescope (and this is a real case) apparently in the Black Sea, rather than
by the nations at war with the
Crimea. Thus astronomically-based time keeping and navigation have
Central Powers with the
long involved exchanges of observations, results of calculations, and time
signals among friendly, and sometimes unfriendly, countries. From a less
eventual co-operation
of neutral nations.”
Resolutions of the Conference of
London, October 1918
practical, astronomical point of view, if you want to catalog all the
objects of some sort in the sky, you will need cataloguers at several latitudes (owing to the earth being round). Continuous monitoring of the
brightness of variable stars means finding collaborators at other longitudes (owing to the sun, unless it is the sun you are monitoring, in which
case the other stars get in the way).
* Just how long a distance is not entirely clear, for while the answer they found
is generally regarded as having been quite accurate, it was given in Roman
stadia, and nobody knows quite how long a stadium was in those days.
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Transits of the sun by Mercury and Venus (historically important in determining the size scale of the solar system), occulations of stars by planets, moons, and
asteroids (which calibrate both precise positions and precise sizes), and eclipses of the sun (with their rare opportunities to see the chromosphere and corona and the
gravitational deflection of light) also all require being in
more than one place at a time or having friends in distant places. All of these activities remain the concern of
members of the International Astronomical Union, along
with a good many others that would never have occurred
to Kepler or Galle, or perhaps even you (but keep tuned).
Contrast, by the way, the situation in physics and chemistry where obviously it is often desirable to have the
same experiment done by two independent laboratories,
exchanging information about their methods and results,
but where there is no need for the times of the experiments to be precisely correlated in advance.
THE CARTE DU CIEL AND ITS CONTEMPORARIES
The compiling of catalogues (meaning tables) and atlases
(meaning pictures) of stellar positions and brightnesses is one of the most ancient of professional astronomical activities, pioneered by Hipparchus (something else
BC) and Ptolemy (moderately AD). Each was able to document about 1000 stars in the part of the sky he could
see. Chinese astronomers in the 12th century and the
last of the naked eye observers (Tycho again, and
Helvelius in 1660) could do no better. The application of
small refracting telescopes increased our reach enormously, and the 1689 and 1797 catalogues of Flamsteed
and Bradley contained about 10,000 stars each.
The advent of dry photographic emulsions toward the
end of the 19th century presented an opportunity to
expand catalogues and atlases by another large factor, as
well as to improve accuracy and repeatability. And, in
Paris in 1889, a group of astronomers representing more
than a dozen countries agreed to divide the sky into zones
and produce a “map of the sky” that would have images
in its atlas of all stars to 14th magnitude (one tenthousandth the brightness of faint stars you can see from
44
WINTER 1997
cities) and positions in its catalogue of all stars to 12th
magnitude. At the urging of David Gill of the U.K. and
Admiral Mouchez (director of the Paris Observatory),
about 20 observatories agreed to participate. This meant
that they would acquire identical telescopes (called astrographs), blanket their parts of the sky with 2 degree
× 2 degree photographic plates, and undertake to publish
their portions of the atlas and catalog. Some of the observatories you have probably heard of—Greenwich,
Paris, Potsdam, Sydney. . .Others will be less familiar—Hyderabad, Tacubaya, Algiers, San Fernando. . .
Potsdam happened to be the only location within the
countries that would eventually lose World War I.
No American observatories were involved, and, in
retrospect, we were very lucky. Even without overlap
between the images, it takes more than 10,000 2 × 2˚ plates
to cover the sky. Most of them were eventually taken,
but, 35 years after the project began, only four of the 20
zones had been completely measured, printed, and distributed (those of Greenwich, Oxford, Perth, and the zone
Hyderabad had originally agreed to do, they took on
another later). The Carte du Ciel was, in retrospect, a
target at which you threw not only money* but also
the irreplaceable time of gifted scientists.
Two other turn-of-the-century international projects
deserve mention. Astronomers had gradually become
more and more interested in how stars are distributed
through space in our galaxy (then widely believed to
be the entire universe). Thus they had diligently been
counting stars as a function of apparent and real brightness, color, motion on the plane of the sky, velocity along
the line of sight, and so forth, picking out whichever bits
of sky appealed to them. Jacobus Kapteyn of Holland
pointed out in 1906 that everybody would get along faster
if they all looked at the same bits of sky, rather than getting radial velocities for one field, colors for another, and
so forth. He suggested about 200 “selected areas,” distributed so as to probe what then seemed to be the salient
features of the galaxy, and naturally, an international
*I think this was originally a description of a golf course: 18
small holes down which you throw money.
committee was appointed (in 1910) to oversee the coordination. It included Kapteyn (succeeded in due course
by van Rhijn, a younger Dutchman), four Anglo-Saxons,
and Kustner, director of the Bonn Observatory. Other
German astronomers were among the most active in providing data pertinent to the selected areas (which, incidentally, are still used for studies of galactic structure).
Finally we come to the International Union for Cooperation in Solar Research, in which George Ellery Hale
(founder of Yerkes, Mt. Wilson, and Palomar Observatories) was the prime mover. They met at least once,
at Mt. Wilson in 1910, discussing, among other issues,
how to standardize measurements of solar rotation made
from different sites, so that real variations across the sun
and with time could be identified. That a strong tradition of international solar astronomy had been established is clear from the early structure of the IAU.
GA in Cambridge (U.K.) in 1925. The IRC eventually
became ICSU, the International Council of Scientific
Unions, and you may very well belong indirectly, because both the U.S. National Academy of Sciences and
IUPAP (the International Union of Pure and Applied
Physics) are, in different ways, member organizations;
I am not prepared to explain exactly what they do.
Additional countries were declared eligible for Union
(or having already been so decided to join up) through
FOUNDING MEMBERS
INTERNATIONAL RESEARCH COUNCIL
Belgium
France
Italy
Poland
Rumania
Brazil
Greece
Japan
Portugal
Serbia
THE WAKE OF THE GREAT WAR
(MOSTLY POLITICAL)
George Ellery Hale was a man not easily discouraged.
With his IUCSR dissolved by the London Conference, he
was at the lead in urging the United States to become
one of the founders of the International Research Council, whose name bears a curious resemblance to that of
the National Research Council, in whose 1916 founding
he also had a hand. Representatives of 16 victorious
nations met in Brussels in July, 1919, and adopted a set
of statutes including the goal of “initiating the formation of international Associations or Unions deemed
to be useful to the progress of science.”
The organizational meeting for the International
Astronomical Union took place at the same time, and
of course Hale was there. An additional 16 nations were
declared eligible for IRC membership over the next few
years, an important constraint on the IAU, since no country could join it, or even, initially, send people to its meetings, without acquiring IRC membership first. Thus the
International Astronomers began as a Union of nine
countries at their first official General Assembly in Rome
in 1922 and had expanded to 22 by end of the second
United States of America
United Kingdom of Great Britain
Australia
Canada
New Zealand
South Africa
COUNTRIES DECLARED ELIGIBLE THROUGH 1922
China
Chili
Spain
Norway
Siam
Denmark
Mexico
Holland
Czecho-Slovakia
the Argentine Republic
Monoco
Sweden
Switzerland
FOUNDING MEMBERS OF THE IAU
Belgium
France
Japan
Canada
Greece
Mexico
Great Britain
Italy
United States
ADDITIONAL IAU MEMBERS TO 1925
Australia
Denmark
Norway
Roumania
aNames
Brazil
Holland
Poland
Spain
Czecho-Slovakia
South Africa
Portugal
Sweden
Switzerland
of countries are as given in original IAU documents.
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45
1939, most notably China and the Soviet Union. Ger-
many, Austria, Hungary, Bulgaria, and Turkey were
patriae non gratae until after the Second World War. The
current list of adhering countries stands at about 60.
Recent additions include entities that were formerly part
of the Soviet Union, Czechoslovakia, and Yugoslavia (entitled to share their parent countries’ memberships as
soon as they join ICSU and start paying IAU dues).
Expressions of interest from Bolivia, Macedonia, and
Central America were considered at the 1997 General
Assembly in Kyoto. Departures from the Union, both
early and recent, most often reflect non-payment of dues
for many years, frequently by small, poor countries.
Recent or threatened losses include Cuba, North Korea,
Azerbaijan, Morocco, and Uruguay. Rumania apparently holds a record, having been admitted three times.
It is currently in good standing.
Traditions established early and still in effect include
cycling the triennial meetings among as many different
countries as are willing and able to host them and choosing officers and Commission Presidents (of which more
shortly) from many and varying countries. Thus we have
met of late in Patras (Greece), New Delhi, Baltimore,
Buenos Aires, The Hague, and Kyoto, and the last six
Union presidents have come from India (Vainu Bappu),
Australia (Hanbury Brown), Japan (Yoshihide Kozai),
USSR/Russia (Alexander Boyarchuk), Holland (Lodewijk
Woltjer), and the U.S. (Robert Kraft). My immediate predecessors and successors as President of Commission 28
(Galaxies)* have been from Holland, Switzerland,
Armenia, Italy, and Japan.
This is perhaps as good a place as any to mention that
the IAU has never had a woman president, though there
have been women members almost from the beginning.
The first three were English speaking (Margaret Harwood, M. A. Blagg, and the redoubtable Annie Jump
Cannon), though at present the French, Italian, and Latin
Jan H. Oort, elected to the IAU in 1925, served as both general
secretary and president, and was the last person to have been
present in Rome in 1922 (though not a registered participant)
and to have attended every General Assembly thereafter,
through 1982. (Courtesy Astronomical Society of the Pacific)
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*If you are saying, “Oh yes. You were elected to this position
for your well-known work on galaxies?” you are not the
first. In fact it was a result of starting up a Supernova Working Group (something to which I have contributed a bit)
which came under Comm. 28 for arcane historical reasons.
THE WORK OF THE UNION—THEN
Colonel F. J. M. Stratton, General Secretary of the IAU before
World War II and president for the “long term” of 1938–1948.
Stratton, a founding member, was apparently the last person
who could say he had attended every general assembly. He
was instrumental in keeping some international contacts alive
during the war period when General Assemblies were
impossible and correspondence difficult. (Courtesy Royal
Astronomical Society Library, Presidential Portrait 48)
American delegations have proportionately far more
women members than the U.K. or the U.S. There have
been two women who served as General Secretary and
a number of female Commission Presidents. I believe
Comm. 28 is the first to have had three, Margaret Burbidge and Vera Rubin having been among my much more
distinguished predecessors.
The IAU differs from virtually all other scientific
unions organized under ICSU in having individual members. The numbers have increased from fewer than 200
at foundation to nearly 8000 after the Kyoto General
Assembly, where about 700 people, most relatively young
(but including Charles H. Townes) were elected, and the
necrology included about 100 names.
The formal structure evolved in Brussels and signed into
effect in Rome consisted of Standing Committees “for
the study of various branches of astronomy, encouragement of collective investigations, and discussion of
questions requiring international agreement or standardization.” The word in the French version of the
Statutes (to this day the official text) was “Commissions,”
which eventually won out over Standing Committees
even in English, perhaps because so many other things
were called Committees (nominating, finance, resolutions, . . . ). Each was to consist of a President and a number of members, originally no two from the same institution. Most Commissions began with 5–20 members,
but, being entitled to co-opt additional members, most
grew steadily, meaning that the effective number of individual members of the Union also grew monotonically.
Thirty commissions started out in Rome. A few, connected with drafting the statutes and choosing the first
cohort of officers, immediately self-destructed. Solar
Radiation (Comm. 10) chose almost immediately to
merge with Solar Physics (Comm. 12), leaving the set
shown in the table at the time of the 1925 General
Assembly, where two more, dealing with the structure
of the Milky Way and diffuse matter in space were
formed. Much of what the Commissions did in the early
days was not just useful but essential in making astronomical research and publications self-consistent and
readable throughout the world. That, on the whole,
astronomers have done more or less what the IAU told
them to do about most of these matters over the intervening 70 plus years is perhaps remarkable. Herewith
some examples.
Notations (Comm. 3): The choice of three-letter abbreviations for the names of constellations, the use of m
and M for apparent and absolute magnitude, astronomical units and parsecs as the units of distance in and out
of the solar system, and a for the semi-major axes of a
binary star orbit are decisions that still stand.
Ephemerides (Comm. 4): All issuers of national
almanacs were persuaded to have their days start at
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COMMISSIONS THEN AND NOW
1925
1
3
4
5
6
7
8
9
10
12
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
1990s
Relativity
Notation
Ephemerides
Bibliography
Telegrams
Dynamical Astronomy
Meridian Astronomy
Astronomical Instruments
Solar Photosphere
Solar Physics
Standard Wave-lengths
Solar Rotation
Planets etc. (Physical)
Lunar Nomenclature
Longitude by Wireless
Variation of Latitude
Minor Planets etc. (Ephemerides)
Disbanded before 1925
Shooting Stars
Carte du Ciel
Stellar Parallax
Stellar Photometry
Double Stars
Variable Stars
Nebulae (& many name changes)
Spectral Classification
Radial Velocities
Time
(Selected Areas, briefly)
founded in 1925
founded in 1925
Disbanded
Disbanded
Ephemerides
Documentation and Astronomical Data
Telegrams
Celestial Mechanics
Positional Astronomy
Instruments & Techniques
(Merged with 12); reborn as Solar Activity
Solar Radiation & Structure
Atomic & Molecular Data
Physical Study of Comets,Minor Planets, & Meteorites
Physical Study of Planets and Satellites
(now done by working group)
Disbanded
Rotation of the Earth
Positions & Motions of Minor planets, Comets, and Satellites
Light of the Night Sky
Meteors & Interplanetary Dust
Merged with 24, 1970
Photographic Astrometry
Stellar Photometry & Polarimetry
Double & Multiple Stars
Variable Stars
Galaxies
Stellar Spectra
Radial Velocities
Time
35
36
37
38
40
41
42
44
45
46
47
48
49
50
51
48
WINTER 1997
Structure & Dynamics of the Galactic System
Interstellar Matter
Stellar Constitution
Theory of Stellar Atmospheres
Star Clusters & Associations
Exchange of Astronomers
Radio Astronomy
History of Astronomy
Close Binary Stars
Astronomy from Space (absorbed 48 in 1994)
Stellar Classification
Teaching of Astronomy
Cosmology (founded 1970)
High Energy Astrophysics (founded 1970)
The Interplanetary Plasma & Heliosphere
Protection of Existing & Potential Observatory Sites
Bioastronomy: Search for Extraterrestrial Life
midnight, like the civil day (though Julian days were
to continue to start at noon, a decision endorsed yet again
this year) and to adopt a standard set of positions for 1054
bright stars used in navigation.
Astronomical Telegrams (Comm. 6): These announced
new astronomical discoveries, observations, and calculations, and astronomers agreed to release things this
way first (even before the New York Times). The Bureau,
originally located in Copenhagen, is now at the Center
for Astrophysics in Cambridge, Massachusetts. Early discoveries were most often comets and asteroids and their
orbits, with an occasional nova. These days we get supernovae, gamma-ray bursts, gravitational lensing events,
and much else. Postcards are still available, but the main
distribution is, of course, electronic.
Standard Wavelengths (Comm. 14): This sounds silly.
Don’t you just go into the laboratory and measure them
with as much accuracy as you need for element identification, radial velocity measurements, or whatever? No,
for several reasons. First, many strong nebular emission
lines are forbidden transitions and cannot be measured
in the lab at all. Second, even at high spectral resolution,
many stellar absorption features are actually blends of
transitions in several elements. Third, even laboratory
values may disagree and must be reduced to some standard (a red cadmium line at 6438.4696 A in those days).
Lunar Nomenclature (Comm. 17, and later commissions and working groups on planetary nomenclature,
etc): Every time a better image reveals a new crater,
moon, or other namable entity, lots of people want to
name it. Someone must adjudicate. Rather impressively,
cooperation in this area survived the USA and USSR both
photographing the moon up close and wanting to name
what they saw for their own assorted heroes.
Meridian Astronomy (Comm. 8), Time (Comm. 31),
Variation of Latitude (Comm. 19) and their successors:
These dealt with the long-standing problem of establishing the variations in the rotation of the earth and the
location of its poles, which feed directly into any accurate
system you want to have either for measuring astronomical positions or for finding yourself on the earth’s
surface, right on down to the GPS.
Solar Rotation (Comm. 15): This was, of course, the
replacement for part of Hale’s solar union.
Carte du Ciel (Comm. 23): Of the three international
projects mentioned in the last section, this is the one
the IAU embraced mostly closely, in part because only
one of the co-operating observatories happened to be located in a Central Powers country, but also partly because
the project had built up an enormous constituency within
the community. By 1925, the Commission was discussing
what else could be done with the plates, especially their
use as the first epoch in a very-long-term proper motion
survey (this is just now beginning to happen). The Commission finally declared itself out of existence and merged
with 24 (by then Parallax and Proper Motion) at the 1970
General Assembly in Brighton, the first one I attended.
IAU “adoption” of the Selected Areas program was also
discussed from the beginning, but postponed because
many of the active participants were German, and they
opposed a structure that would exclude them from any
decision-making. The problem resolved by the fifth General Assembly in 1935 and Selected Areas became Commission 32 (later merging with 33, Milky Way).
Variable Stars (Comm. 27): The members provided a
list of stars that, because of having periods very long,
very short, or nearly commensurate with 24 hours,
needed international attention to pin down their
properties. Some of the ones listed, like R CrB and SS Cyg,
are still rather a puzzle (though astrophysically rather
than temporally).
THE WORK OF THE IAU—NOW
According to my notes from Kyoto, the IAU now has
39 Commissions and four independent Working Groups.
Some of them still deal with issues that go back to the
beginning: Planetary System Nomenclature (a working
group), Astronomical Telegrams (Comm. 6), Atomic and
Molecular Data (Comm. 14, dealing with standardized
wavelengths but also transition probabilities and other
useful numbers), Rotation of the Earth (Comm. 19),
Ephemerides (Comm. 4), and Documentation and
Astronomical Data (Comm. 5, which these days includes
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non-paper archiving). A few commissions still have only
20–40 members. Others (including Galaxies, Radio
Astronomy, and Astronomy from Space) exceed 600. A
good many have been renamed, and some numbers have
been recycled. But the commissions are still telling us
what to do, including, for instance, the need for a more
accurate description of the rotation of the earth, a standardized way of correcting times of astronomical observations for effects of general relativity, and the Julian
Day (it still starts at noon, but the Modified Julian Date
starts at midnight, and PLEASE be sure to tell us which
you are using!). Yet another resolution dealt with making the new coordinate system established by the
Hipparcos satellite nest properly with ground-based optical and radio coordinates. This last matters even for
ordinary science; if you want to know whether the radio
and optical knots in the jet of a quasar are correlated
or anti-correlated on sub-arcsecond scales, you had better be able to line up the two sets of data to 0.1 arcsec
or thereabouts.
The Union and its Commissions have, however, also
moved strongly in three directions not envisaged by the
founders. The first consists of things about which one
can say, with old Ben Franklin, that if we do not hang
together, we will all hang separately. The entities called
Protection of Existing and Potential Observing Sites
(Comm. 50), Future Large Scale Facilities, Encouraging
the International Development of Antarctic Astronomy
(Working Groups), and the part of Radio Astronomy
(Comm. 40) that fights for protected frequencies come
under this heading. Second, the IAU has become much
more active in promoting astronomy in developing countries. It puts money into three activities along these lines:
1. Exchange of Astronomers (Comm. 38), which administers travel grants for astronomers working under
difficult circumstances to pay 3–12 month visits to larger
observatories and universities. A few grants also go to
people from prosperous places going to less prosperous
ones primarily to bring their host organizations into main
stream activities. We also send a good many free books.
2. An on-going series of both regional meetings (normally in Latin America and in the Asia-Pacific areas) and
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WINTER 1997
international schools for young astronomers from regions
centered around the host country—most recently Iran
and China.
3. Teaching of Astronomy (Comm. 46) again focuses
on developing countries and has coordinated recent workshops for teachers in Vietnam and Central America, with
ones in Sri Lanka and Morocco contemplated if funding
can be found. This Commission also addresses the problem of teaching astronomy to interested students, uninterested students, and the general public in developed
countries.
Third is the great increase in the amount of science
presented and discussed at the General Assemblies and
at IAU-sponsored symposia and colloquia in non-GA
years. Proposals can come from anyone in the astronomical community, but must be endorsed and evaluated by the Commissions most relevant to the topics.
The number of proposals typically exceeds the 5–6 symposia and 5–6 colloquia that can be funded each year
by a factor of about two. The winners have several things
in common. One is scientific merit. But, in addition, the
proposals must have broad international representation
on their scientific organizing committees and among the
invited speakers; organizers must agree to use some of
the IAU money for travel grants for young astronomers
and those from less developed countries; and the host
country must agree to admit participants from every
country. The sites are widely scattered. Events scheduled in 1998 will occur in Canada, Spain, Armenia,
France, South Africa, Mexico, China, Germany, and probably a couple of other places. And topics include the full
range of solar system, stars, galaxies, and the universe.
The most recent General Assembly in August 1997
in Kyoto had a program with six symposia of about four
days each (on topics from helioseismology to cosmology), 23 joint discussions of a day or so (ranging from
the New International Celestial Reference Frame to The
Megamaser-Active Galaxy Connection), brief business
meetings of most of the divisions, commissions, and
working groups, special sessions on Comet Hale-Bopp,
early results from the Infrared Space Observatory (a
largely European satellite), and some other entities whose
FINANCES
Sums of money from the past always sound ridiculously
small. The early IAU accounts were kept in British
pounds (though legally assessed in French francs), so the
proper comparison is with the £100 a year on which a
single woman could live comfortably and “£10,000 a
Year,” the title of a book supposed to describe riches beyond the dreams of middle class avarice in about 1920.
Thus it was that the Union had an average annual income of £1500 between 1922 and 1925, nearly all of it the
contributions from member countries. These, like the
dues for the International Research Council, were assessed in proportion to the populations of the nations,
with cuts at 5, 10, 15, and 20 million. The U.S. population in 1920 was 108 million, and, in the first few years,
we contributed 11 percent of the budget, while making
up 24 percent of the membership.
One aspect of this has changed hardly at all. American membership is still pretty close to 25 percent of
the total; and our 1997 assessed dues are 86,400 Swiss
francs in a total of 716,280, or 12 percent. Expected
contributions are now more nearly proportional to
Virginia Trimble
acronyms I cannot decode, plus a countably infinite number of committee meetings. Maximal packing occurred
on Monday, August 25, with 14 simultaneous activities.
About 2000 people participated in these festivities,
roughly 700 from the host country and a smaller number from the U.S. (the second largest delegation). That
most genuinely participated shows in the number of
posters presented (1600 in four three-day shifts of 400
each) and talks (about 900, all the way from hour-long
reviews of black holes at galactic centers and convection in stars to 10-minute news flashes on rapid evolution of a particular binary star and X-ray after-glows from
gamma ray bursts). The American participants did their
fair share, but probably not more: in the three joint discussions I participated in, there were 5 American speakers out of 21 (stellar evolution on short time scales), 3 of
20 (early results from the Hipparcos astrometric satellite), and 9 of 25 (high energy transient sources).
Lodewijk Woltjer, IAU president 1994–1997 bids farewell to
participants at the Kyoto General Assembly during the
closing ceremonies. His father, Jan Woltjer, was a founding member of Commission 7 (Dynamical Astronomy)
numbers of astronomers in the countries than to total
populations, and there is some additional income from
publications and other sources. Sporadic special contributions, primarily from the U.S., have added about
200,000 Sfr each triennium, but are earmarked to pay for
travel by people from the contributing country.
Where did the money go? In the early days, mostly to
subsidize the practical activities of time keeping, monitoring of latitude, and so forth; to support publications;*
and to operate the office of the general secretary, who in
1923 took a 10s 8p train ride, had a £26 ls 9p part-time
secretary, and bought £8s 9p worth of postage stamps.
Where does the money go? Now, very considerably
for science. In the 1994–96 triennium, total outgo was
2,526,601 Swiss francs, somewhere between $1.6 and $2.2
*The Carte du Ciel was a bottomless fiscal hole for the IAU
as well as for the participating observatories, swallowing
£100 here and £47 there several times a year to publish
bits and pieces of the catalog.
BEAM LINE
51
million at any given moment, owing to wildly variable exchange rates. Of this, 45 percent directly supported
scientific meetings involving astronomers from all over
the world (primarily as travel grants). Another 11 percent was for activities aimed specifically at developing
countries—schools, regional meetings, free copies of IAU
symposium proceedings, etc. About 12 percent was
widely scattered over dues to ICSU and other umbrella
organizations, distribution of information to members,
archiving, and the traditional support of the telegram
bureau, variable star catalogues, and so forth, now down
to 1 percent of expenditures. The Carte du Ciel did not
get a penny.
Finally (and quite typical for scientific societies), the
last third of the budget paid for the secretariat, officers’ meetings, bank charges, and such. More than half
is salaries, and, of course, the people involved spend
nearly all their time coordinating astronomical symposia, publications, activities in developing countries,
and all the rest. And, for better or for worse, the share of
travel grants going to American astronomers is, on average, slightly larger than the fraction of the income we
contribute.
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MORE ABOUT THE IAU
PAST AND PRESENT
Lankford, John 1997. American Astronomy: Community,
Careers, and Power, 1859–1940, University of
Chicago Press, notes how we benefited from not
contributing to the Carte du Ciel.
Blaauw, Adriaan 1994. History of the IAU (Dordrecht:
Kluwer), is the definitive source, especially on the
early days and on how the Union survived the very
awkward issues involving the USSR, USA, and two
Chinas during the cold war.
IAU Publications: These all appeared under the Reidel
(later Kluwer) label for many years, but will be
published by the Astronomical Society of the
Pacific beginning in 1998. Symposia are the usual
sorts of conference proceedings. Highlights include the science from the General Assemblies.
And Transactions A are triennial compilations of
the highlights of research in the fields of each of
the Commissions, assembled by the Commission
officers.
Databases and International
Collaboration
by PAT KREITZ & MICHAEL BARNETT
S
TUDENTS AND RESEARCHERS searching the SPIRES-HEP databases
or consulting the Review of Particle Physics are reaping the benefits of two of
the longest standing international collaborations in high energy physics. For
decades, each of these collaborations has been working quietly and effectively to
provide the field with core reference tools. Together these grass-root efforts produce
a comprehensive, up-to-date, and highly accurate suite of resources supporting particle physics that are the envy of researchers and students in other fields. The fact
that these tools are available free to the desktops of the worldwide particle physics
community is unique and, in fact, only possible through the cost-effective tool of
international collaboration.
The SPIRES-HEP collaboration, a joint project between the Stanford Linear Accelerator
Center (SLAC) and the German Deutsches
Elektronen Synchrotron (DESY) libraries with
significant assistance from the Japanese High
Energy Accelerator Research Organization
(KEK) and the Japanese Yukawa Institute for
Theoretical Physics, Kyoto University, produces a number of databases which provide
comprehensive access to the literature of high
energy physics as well as to conferences, people, institutions, and experiments in the field.
The core database, known as SPIRES-HEP, contains over 355,000 records for preprints, articles, reports, and theses from 1974 to the present. The database contains World Wide Web
links to the full text of papers when available,
with over 100,000 such links currently in the
database. These links are provided by cooperative efforts with the Los Alamos Electronic
Preprint (E-Print) Archive, other laboratories,
journal publishers, individual physics departments, and experimental groups.
Many other laboratories and physics groups
such as CERN in Switzerland, Fermilab in Illinois, and the Institute of High Energy Physics
(IHEP) in Serpukhov, Russia, contribute to and
download information from the SPIRES-HEP
system. The American Physical Society’s
Physical Review D supplies SLAC with advance links to papers accepted for publication and in return downloads SPIRES-HEP citation data and links into their system. The
LANL E-print Archive has collaborated with
SPIRES-HEP since its inception in 1991. Links
in SPIRES-HEP are created nightly to the
preprints posted at Los Alamos National Laboratory, and the LANL system downloads
SPIRES-HEP cataloging data and citation links.
Three sites, Yukawa Institute, DESY, and
Durham (U.K.), run full mirror copies of
SPIRES-HEP, while IHEP runs a partial mirror
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53
site. Since the beginning, the SPIRESHEP collaboration and the Particle
Data Group have had a productive
history of collaborative support and
development.
For forty years the Particle Data
Group has been an international collaboration that reviews particle
physics and related areas of astrophysics and compiles and analyzes
data on particle properties. The PDG
produces the Review of Particle
Physics (RPP) and the Particle Physics
Booklet. These are distributed to
30,000 physicists, teachers, students,
and other interested people around
the world. The heavily used PDG
website provides access to most of
the data listings and reviews.
There are several centers of PDG
work including Lawrence Berkeley
National Labortory, CERN, KEK,
IHEP, SLAC, and INFN, Italy. How-
ever, all of the work is done in collaboration with over a hundred outstanding particle physicists and astrophysicists from throughout the world.
In addition the PDG is in frequent
contact with 700 leaders of particle
physics experiments. The PDG work
is the product of efforts by a large fraction of the entire particle physics
community. Quality is maintained in
part by yearly meetings of an international advisory committee.
Collaborative distribution of effort has enabled the PDG to manage
the growing body of literature in the
field and to enhance and expand coverage over the past fifteen years,
which has seen a tripling of the number of papers added to each edition,
and a tripling of the number of reviews. The most recent edition had
1900 new measurements from 700 papers, in addition to the existing 14,000
measurements from 4000 papers.
Each new edition is eagerly awaited by the particle physics community, as evidenced by big jumps in the
usage of the PDG website.
High-energy physics’ strong tradition of international collaboration
has been an effective model for efforts
such as SPIRES-HEP and the Particle
Data Group, enabling them to manage increasing work loads cost effectively, take advantage of distributed,
specialized expertise, and continue
to create useful and freely accessible
research support tools for the particle
physics community. Both of these collaborations are made possible not only
by the institutional commitments of
many organizations but by the personal effort and dedication of individual physicists and support staff
who give their time for the good of
the entire community.
Most Cited Particle Physics Publication
A search in the SPIRES-HEP database to discover how many times the various editions of the Particle Data Group’s RPP
has been cited shows that it is the most heavily cited publication in particle physics. Since 1974 the total for all editions of the
RPP is an impressive 10,123 citations. The most recent edition (below) is supplemented by web-accessible updates of the
reviews, tables, and plots and the 1997 Particle Listings.
Review of Particle Physics by the Particle Data Group, R. M. Barnett, C. D. Carone, D. E. Groom, T. G. Trippe, C. G. Wohl,
B. Armstrong, P. S. Gee, G. S. Wagman, Lawrence Berkeley National Laboratory; F. James, M. Mangano, K. Monig, L. Montanet, CERN; J. L. Feng, H. Murayama, LBNL and UC, Berkeley; J. J. Hernandez, Valencia University; A. Manohar, UC, San
Diego; M. Aguilar-Benitez, Madrid, CIEMAT, and CERN; C. Caso, Genoa University and INFN, Genoa; R. L. Crawford, Glasgow University; M. Roos, N. A. Tornqvist, Helsinki University; K. G. Hayes, Hillsdale College; K. Hagiwara, K. Nakamura,
M. Tanabashi, KEK; K. A. Olive, Minnesota University; K. Honscheid, Ohio State University; P. R. Burchat, Stanford University; R. E. Shrock, SUNY, Stony Brook; S. Eidelman, IYF, Novosibirsk; R. H. Schindler, SLAC; A. Gurtu, Tata Institute;
K. Hikasa, Tohoku University; G. Conforto, Urbino University and INFN Florence; R. L. Workman, Virginia Tech; C. Grab,
ETH, Zurich; C. Amsler, Zurich University; July 1996, 720 pp.
Formerly titled Review of Particle Properties, Published in Phys. Rev. D54, 1-720 (1996). The 1996 Review of Particle
Physics with 1997 updates is available on the web at http://pdg.lbl.gov/pdg.html.
Two popular compilations based on the SPIRES-HEP database’s citation searching feature, the “Top-Cited HEP Articles,
1998 Edition” and the “All-Time HEP Favorites: 1998 Edition” are being edited by Michael Peskin of SLAC and will soon be
available at http://www-spires.slac.stanford.edu/FIND/spires.
54
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FROM THE EDITORS’ DESK
T
HIS SPECIAL ISSUE of the Beam Line is devoted
to international collaboration in the field of particle physics research. It is a part of our continuing
effort to describe new developments from around the globe,
and to hear from the people who are doing and reporting the
work. In this regard, we want to welcome three new contributing editors to
our team and masthead: Judy Jackson
from Fermilab, DESY’s Pedro Waloschek, and Gordon Fraser, the Editor of
the CERN Courier. In addition to crafting
their own articles, they will be on the
lookout for contributors in their own
Gordon Fraser
domains of the high energy physics community. So if you have an idea for an article and would like
some help putting your thoughts on paper, by all means contact one of them (or one of us) for help or advice.
Meanwhile, we’ve also had a changing of the guard in the
Beam Line Editorial Advisory Board. James Bjorken, Robert
Cahn, and David Hitlin are stepping down after long and productive tenures, to be replaced by Lance Dixon of SLAC,
George Trilling of Lawrence Berkeley National Laboratory,
and Karl van Bibber from Lawrence Livermore National
Laboratory.
It’s been a good year for the Beam Line. We expect the new
and expanded editorial team to help us keep it going.
Judy Jackson
Pedro Waloschek
BEAM LINE
55
CONTRIBUTORS
S. PETER ROSEN is Associate GORDON FRASER studied at H IROTAKA S UGAWARA
Director of High Energy and Nuclear
Physics for the Department of
Energy. He was educated at Oxford
University and came to the United
States to work with the late Henry
Primakoff on double beta decay in
1957 as a research associate at Washington University. After a staff position at the Midwestern Universities Research Association and a
NATO Fellowship at Oxford, he
joined the faculty of Purdue University. In 1983, he joined Los Alamos
National Laboratory as Associate
Leader of T-Division for high energy
and nuclear physics, and in 1990 he
went to the University of Texas at
Arlington as Dean of Science. He
started his present position in January 1997. His scientific interests include weak interactions, symmetries,
and properties of the neutrinos,
especially solar neutrinos.
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WINTER 1997
London’s Imperial College in the
mid-1960s, when theoretical physicists were attacking spontaneous
symmetry breaking under Tom Kibble and relativistic SU(6) theory under Abdus Salam and Paul Matthews.
Fraser also wrote short-story fiction
and became side-tracked into journalism. He returned to physics as a
science writer, eventually transferring to CERN. He is editor of the
monthly CERN Courier; co-author,
with Egil Lillestol and Inge Sellevag,
of The Search for Infinity (New York,
Facts on File, 1995) which has been
published in ten other languages; and
author of The Quark Machines (Bristol, Institute of Physics Publishing,
1997). He is also editor of Particle
Century, a collection of contributions
to be published by Institute of
Physics Publishing later this year.
is
Director General of the High Energy
Accelerator Research Organization
(KEK) in Tsukuba, Japan. He was educated at the University of Tokyo,
and prior to his appointment as a professor there he held research associate positions at Cornell University,
the University of California, Berkeley, and the University of Chicago.
He has also held visiting professorships at New York University, the
University of Hawaii, the University
of Chicago, and École Polytechnique
in Paris.
ALEXANDER SKRINSKY is di- ZHOU GUANGZHAO is a spe- GEORGE TRILLING is Profesrector of the Budker Institute of Nuclear Physics Siberian Branch of the
Russian Academy of Sciences. Prior to his becoming director in 1978,
he served as deptuy director. A member of the Russian Academy of Science, he is presently executive secretary for Nuclear and High Energy
Physics.
He has served as a past chairman
of ICFA, the International Committee on Future Accelerators, and as a
member of the CERN Scientific Policy Council. He is preently a member of the Extended Scientific Council for DESY.
Skrinsky was awarded State Prizes
in 1967 and 1989. He has written over
300 publications in the field of accelerator physics and technology.
cial advisor to the Chinese Academy
of Sciences and served as president
from 1989–1997. A theoretical nuclear
physicist, Zhou has made important
contributions to the theory of weak
interactions. He studied in Beijing
under Peng Huanwu, Max Born’s first
Chinese student. He also trained at
the Joint Institute for Nuclear
Research at Dubna in the Soviet
Union.
He is vice president for the Chinese People’s Association for Peace
and Disarmament and chairman of
the China Association for Science
and Technology.
sor Emeritus in the Physics Department of the University of California,
Berkeley, and a member of the staff
of the Lawrence Berkeley National
Laboratory. He received his BS and
PhD from Caltech. Since his move
to Berkeley in 1960, he has served
as Physics Department Chairman,
Director of the LBNL Physics Division, and chaired SLAC’s Scientific
Policy Committee. He is a member
of the National Academy of Sciences
and the American Academy of Arts
and Sciences.
His research interests have been
in high energy experimental physics,
and have included hadron resonances, high energy electron-positron
annihilation, and colliding-beam experiments at the highest energies. He
has recently been involved in the negotiations between CERN and U.S.
funding agencies relative to U.S. participation in the Large Hadron Collider project.
BEAM LINE
57
M.G.D. (“Gil”) GILCHRIESE DAN GREEN is a research scien- G REGORY L OEW is Deputy
is a Senior Physicist at Lawrence
Berkeley National Laboratory (LBNL).
After obtaining a PhD from Stanford
University for work at Stanford Linear Accelerator Center in 1977, he
worked for one year on neutrino experiments at Fermi National Accelerator Laboratory for the University of Pennsylvania, and then joined
the faculty of Cornell University just
in time to experience the startup of
the CESR facility and the CLEO detector. After eight years in snowy
Ithaca, he moved to Berkeley to work
with the SSC Central Design Group,
and then later to Texas with the SSC
Laboratory. He is currently the manager of the Silicon Subsystem for the
U.S. ATLAS collaboration at CERN.
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tist at Fermi National Accelerator
Laboratory and actively involved in
the CMS hadron calorimeter subsystem for the Large Hadron Collider at
CERN. His interest in hadron colliders can be traced back to his
Intersecting Storage Ring work at the
Pisa-Stony Brook experiment at
Brookhaven National Laboratory in
the 1970s. More recently he was the
leader of the D0 muon subsystem at
Fermilab and the calorimeter system
leader and deputy spokesperson for
the SDC experiment at the Superconducting Super Collider. Following the demise of the SSC, he led the
formation of the U.S. CMS collaboration and is presently its spokesperson. In odd moments he has authored
a book, Lectures in Particle Physics,
and is writing another, The Physics
of Particle Detectors.
Director of SLAC’s Technical Division and a member of the SLAC
Faculty. In 1958 he joined Project M,
which was later to become SLAC, to
design the constant-gradient accelerator structure for the threekilometer linac. Since then he has
had many diverse assignments at the
laboratory, in the international
accelerator community, and in various committees of the American
Physical Society. Starting in 1994, he
led the International Linear Collider
Technical Review Committee which
produced the report mentioned in the
article. In 1996, he chaired the APS
Committee on the International
Freedom of Scientists. Last October
he met many of his colleagues at
LC97 in Zvenigorod, Russia, and
chaired one of the working groups at
this most recent international
electron-positron linear collider
workshop (group photo at top of
page 38).
MICHAEL RIORDAN has spent VIRGINIA TRIMBLE, one of the Vice Presidents of the International
much of his last twenty years writing and editing general books on science, technology, and their impact
on our lives. They include The Solar
Home Book ( 1977), The Day After
Midnight (1981), The Hunting of the
Quark (Simon & Schuster, 1987), The
Shadows of Creation (W. H. Freeman,
1991), and Crystal Fire: The Birth of
the Information Age (W. W. Norton,
1997).
He currently divides his working
time between SLAC, where he serves
as Assistant to the Director and Contributing Editor of the Beam Line, and
the Santa Cruz Institute of Particle
Physics, where he is researching a
scholarly history of the Superconducting Super Collider. For recreation he can often be found paddling
his kayak on the waters of Monterey
Bay or hiking near his home in the
Santa Cruz mountains.
Astronomical Union, and Past President Alexander Boyarchuk of
Moscow may give the impression that the cold war is not quite over, but
they were in fact separated only by a table leg, not political or scientific
issues, during the closing ceremonies of the Kyoto General Assembly in
August 1997.
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DATES TO REMEMBER
Mar 1–7
12th Les Rencontre de Physique de la Vallee d’Aoste: Results and Perspectives in Particle
Physics, La Thuile, Aosta Valley, Italy (Giogio Bellettini, Dipartimento di Fisica, Universita de
Pisa, INFN, Sezione di Pisa, Italy, or chiarelli@axpia.pi.infn.it)
Mar 12–20
Joint Universities Accelerator School (JUAS 1998) on Accelerator Physics and Accelerator Technology, Archamps, France (juas@cern.ch)
Mar 16–20
1998 American Physical Society Meeting, Los Angeles, California (www.aps.org/meet/index.html)
Mar 22–27
6th International Symposium on Particles, Strings, and Cosmology (PASCOS 98), Boston, Massachusetts (Donna M. Hawkins, Department of Physics, Northeastern University, Boston, MA
02115, or utpal@albert.physics.neu.edu)
Mar 30–Apr 7
Spring School and Workshop on String Theory, Gauge Theory, and Quantum Gravity, Trieste,
Italy (ICTP, Box 586, I-34100 Trieste, Italy, or smr1090@ictp.trieste.it)
Apr 1–7
Tropical Workshop on Particle Physics and Cosmology, San Juan, Puerto Rico (Jose F. Nieves,
Department of Physics, University of Puerto Rico, Rio Piedras, Puerto Rico 00931-3343, or
nieves@ltp.upr.clu.edu)
Apr 4–8
6th International Workshop on Deep Inelastic Scattering and QCD (DIS 98), Brussels, Belgium
(DIS98, IIHE, Pleinlaan 2, 1050 Brussels, Belgium, or dis98@hep.iihe.ac.be)
Apr 8–11
2nd Latin America Symposium on High-Energy Physics (SILAFAE 98), San Juan, Puerto Rico
(Jose F. Nieves, Department of Physics, University of Puerto Rico, Rio Piedras, Puerto Rico
00931-3343, or nieves@ltp.upr.clu.edu)
Apr 18–21
1998 Joint APS/AAPT Meeting, Columbus, Ohio (www.aps.org/meet/index.html)
May 4–7
8th Beam Instrumentation Workshop (BIW 98), Stanford, California (Suzanne Barrett, SSRL,
SLAC, Box 4349, Stanford, CA 94309-0210, or biw98@slac.stanford.edu)
May 12–14
1998 Symposium on Radiation Measurements and Applications, Ann Arbor, Michigan
(9thSymposium@umich.edu)
May 18–22
Workshop on Accelerator Operations (WAO 98), Vancouver, Canada (Fred Bach, Secretary,
TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, Canada V6T 2A3, or music@triumf.ca)
Jun 14–21
5th International Wein Symposium: A Conference on Physics Beyond the Standard Model,
Santa Fe, New Mexico (WEIN 98, Mail Stop H844, Los Alamos National Laboratory,
Los Alamos, NM 87545, or wein98@lanl.gov)
Jun 22–26
6th European Particle Accelerator Conference, Stockholm, Sweden (C. Petit-Jean-Genaz,
CERN-AC, 1211 Geneva 23, Switzerland, or christine.petit-jean@cern.ch)
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